Reginald Punnett, in full Reginald Crundall Punnett, (born June 20, 1875, Tonbridge, Kent, England—died January 3, 1967, Bilbrook, Somerset), English geneticist who, with the English biologist William Bateson, discovered genetic linkage.
Educated at the University of Cambridge, Punnett began his professional research with structural studies of marine worms. Later his interest turned to genetics, and, while a demonstrator in zoology at Cambridge (1902–05), he joined a genetic study group under Bateson. Through his contact with Bateson, Punnett came to support the theories of Gregor Mendel, the founder of modern genetics. Subsequently, he wrote Mendelism (1905), the first textbook on the subject.
Using poultry and sweet peas, Punnett and Bateson discovered some of the fundamental processes of Mendelian genetics, including linkage, sex determination, sex linkage, and the first example of autosomal (nonsexual chromosome) linkage. In 1910 Bateson and Punnett founded the Journal of Genetics, which they jointly edited until Bateson’s death (1926). In 1912 Punnett became a fellow of the Royal Society of London and was named professor of genetics at Cambridge.
During World War I, when many foods were scarce, Punnett pointed out the value of employing sex-linked plumage-colour factors to distinguish male from female chickens; early identification of the less valuable males was thus made possible. The process, known as autosexing, is treated in his Heredity in Poultry (1923).
R. C. Punnett, the codiscoverer of linkage with W. Bateson in 1904, had the good fortune to be invited to be the first Arthur Balfour Professor of Genetics at Cambridge University, United Kingdom, in 1912 when Bateson, for whom it had been intended, declined to leave his new appointment as first Director of the John Innes Horticultural Institute. We here celebrate the centenary of the first professorship dedicated to genetics, outlining Punnett’s career and his scientific contributions, with special reference to the discovery of “partial coupling” in the sweet pea (later “linkage”) and to the diagram known as Punnett’s square. His seeming reluctance as coauthor with Bateson to promote the reduplication hypothesis to explain the statistical evidence for linkage is stressed, as is his relationship with his successor as Arthur Balfour Professor, R. A. Fisher. The background to the establishment of the Professorship is also described.
THE centenary of the foundation of Cambridge University’s Professorship of Genetics in 1912 provides a timely occasion to recall the contributions of its first holder, Reginald Crundall Punnett (1875–1967; Figure 1). Overshadowed by his senior colleague William Bateson (1861–1926), for whom the Professorship had been intended, and his successor R. A. Fisher (1890–1962), Punnett played an important role in the early days of Mendelian genetics. He wrote the first genetics textbook Mendelism (Punnett 1905), collaborated in the discovery of partial coupling (linkage), asked G. H. Hardy the question that led to the formulation of what became known as Hardy–Weinberg equilibrium, published Mimicry in Butterflies (Punnett 1915) and Heredity in Poultry (Punnett 1923a), and pioneered the use of sex-linked markers for sexing poultry chicks. He founded the Journal of Genetics with Bateson in 1911 and edited it alone after Bateson’s death. He was the first Secretary and was later President of the Genetical Society of Great Britain. His name is immortalized in “Punnett’s square” (Figure 2).
R. C. Punnett. Courtesy of the Master and Fellows of Gonville and Caius College, Cambridge.
Punnett’s square, from the Second Edition of Mendelism (Punnett 1907).
F. A. E. Crew (Crew 1967) wrote Punnett’s biographical memoir for the Royal Society, to which Punnett was elected in 1912, and followed this with a shorter account for GENETICS (Crew 1968). In the opening paragraph of the latter he said that Punnett “had the good fortune to be an active participant in the work that confirmed and extended the findings of Gregor Mendel when these were brought to light in 1900. He lived, therefore, in a period that was filled with excitement and could rightly feel that he was involved in a great adventure that would surely lead to a revolution in biological thought.” Crew’s memoirs should be consulted for details of Punnett’s life; here I concentrate on his scientific contributions and give only a brief biographical summary.
Punnett was born to George and Emily Punnett (née Crundall) at Tonbridge, Kent, on June 20, 1875. Both parents were of Kentish stock. He was educated at Clifton School, Bristol, and Gonville and Caius College, Cambridge, which he entered as a scholar in 1895. Originally registering as a medical student, he took the Natural Sciences Tripos, specializing in zoology in his third year and being placed in the first class in the Tripos in 1898. He spent the next year at the Naples Zoological Station (Naples, Italy) and at Heidelberg University (Heidelberg, Germany) and in September 1899 accepted the post of Demonstrator in the Natural History Department of the University of St. Andrews (St. Andrews, Fife, Scotland). In October 1901 a Fellowship of Gonville and Caius College followed, capped by the University post of Demonstrator in Morphology, which he held until 1904, when he became Balfour Student in Zoology. This studentship, in memory of Francis Balfour, Professor of Animal Morphology, Arthur Balfour’s brother, had been held by William Bateson from 1897 to 1900.
Then in 1908 Punnett started a rapid rise up the academic ladder. Still with his Caius Fellowship (which he was to retain until his death) he became Demonstrator in Animal Morphology in the Department of Zoology, Superintendent of the Museum of Zoology in 1909, and, when Bateson resigned his Professorship of Biology in 1910 to take up the Directorship of the John Innes Institute, Punnett succeeded to it. In 1912 the Arthur Balfour Professorship of Genetics was founded and, following the failure of the University to attract Bateson back from his Directorship, Punnett was appointed. We consider the history of the Professorship in a later section.
At Naples in 1899 Punnett started to study the morphology of nemertine (or “Nemertean”) marine worms, and these continued to be his main interest at St. Andrews and on his return to Cambridge. In 1903 he embarked on a statistical study “On nutrition and sex-determination in man,” using data for London from the 1901 Census, which revealed a modest facility in handling numbers (Punnett 1903). The human sex ratio was my own Ph.D. topic and in 1959 I must have heard about his interest and sent him an offprint of one of my articles (Edwards 1958) for I still have his letter in reply.
Punnett’s association with Bateson started at the beginning of 1904. Some time earlier, “Knowing that Bateson was carrying out Mendelian experiments at Merton House, Grantchester, [Punnett] wrote to him suggesting that perhaps his nutritional experiments might be so designed that they would yield information concerning the inheritance of coat colour [in the mouse]” (Crew 1967). When Bateson received an offer of financial support from his friend Mrs. Christiana Herringham in December 1903, he first thought of Leonard Doncaster as an associate, but Doncaster declined (Cock and Forsdyke 2008, p. 217) and so he wrote to Punnett (on Christmas Day), inviting him to come “into partnership in my breeding experiments.” “Mr. Punnett joined with enthusiasm, and very generously refused the ... salary” (Bateson 1928, p. 87), “... and so a partnership that was to last six years and that was to make notable and enduring contributions to genetics came into being. The two men were very different temperamentally, Bateson was a forceful personality, combative and stern; Punnett was retiring, tolerant and friendly; it was a happy and harmonious partnership” (Crew 1967).
In 1913 Punnett married Eveline Maude Froude, widow of Sidney Nutcombe-Quicke. They lived in Whittingehame Lodge, Storey’s Way, Cambridge, in the house provided for the Arthur Balfour Professor, until Punnett retired in 1940 at the age of 65. He and his wife then moved to Bilbrook, near Minehead, Somerset, where he died on January 3, 1967. There were no children.
Crew’s (1967) biographical memoir contains a list of Punnett’s publications and summaries of his work beyond the topics I discuss in detail here. In the summer of 1909 Punnett had visited Ceylon to study mimetic butterflies, where he met his Caius colleague R. H. Lock, then Assistant Director of the Royal Botanical Gardens at Peradeniya (Sri Lanka). The visit led to a handsomely illustrated book Mimicry in Butterflies (Punnett 1915). “... it included a mutationist’s explanation for the evolution of complex mimetic resemblances between members of unrelated species” (Bennett 1983, p. 8). R. A. Fisher’s view of their evolution was completely different. He set it out in Fisher (1927) and in Chapter VIII, “Mimicry,” of The Genetical Theory of Natural Selection (Fisher 1930a) with special reference to Punnett’s view in the section “The theory of saltations.” Provine (1971, p. 150) gives an account. On evolution Fisher and Punnett were to cross swords again when Punnett reviewed The Genetical Theory, which we refer to below under Population Genetics.
Punnett’s experience with studying Mendelian characters in poultry led him to invent the method of using sex-linked plumage color factors to sex day-old chicks, thus enabling the unwanted majority of cockerels to be disposed of immediately. By 1940 he had published, alone or jointly, 11 “Genetic studies in poultry,” with another two to come in retirement in 1948 and 1957. Crew (1968) may be referred to for further details, for unlike the biographical memoir for the Royal Society his memoir in GENETICS contains a substantial extract by Professor F. B. Hutt “whose Genetics of the Fowl is in the direct line of Punnett’s Heredity in Poultry, 1923a” (Crew 1968).
Punnett (1928) edited Bateson’s scientific articles for Cambridge University Press. T. H. Morgan (1929) reviewed the two volumes in Nature, regretting the omission of the Reports to the Evolution Committee (see below), which were represented only by summaries. After Bateson’s death in 1926, Punnett (1926) wrote a memoir of him in the Edinburgh Review, part of which was reprinted in Notes and Records of the Royal Society in 1952 (Punnett 1952).
he work for which Punnett is best remembered, the discovery of linkage jointly with William Bateson, arose out of their studies of Mendelian ratios in the sweet pea Lathyrus odoratus. The discovery is more properly referred to as “partial coupling” because the word “linkage” had not yet been coined in this connection, nor had its chromosomal basis been postulated. The analysis of the various ratios that characterized Mendelian inheritance was much facilitated by Punnett’s simple square diagram showing how gametes combine to make zygotes or sometimes how genotypes at two loci combine to make zygotes. Punnett’s square seems to have been a development of 1905, too late for the first edition of his Mendelism (May 1905) but much in evidence in Report III to the Evolution Committee of the Royal Society [(Bateson et al. 1906b) “received March 16, 1906”]. The earliest mention is contained in a letter to Bateson from Francis Galton dated October 1, 1905 (Edwards 2012). We have the testimony of Bateson (1909, p. 57) that “For the introduction of this system [the ‘graphic method’], which greatly simplifies difficult cases, I am indebted to Mr. Punnett.” As we shall see, 1905 was also an important year in the discovery of partial coupling, so the two developments went hand in hand. Here we give the salient features of Punnett’s square, relying on the extended account by Edwards (2012), which is fully illustrated.
The first published diagrams appeared in 1906. On February 1 Bateson, in an address to the Neurological Society (Bateson 1906), displayed the 9:3:3:1 Mendelian ratio among the F2 for two loci when dominance is complete at both. Then Report III contained several, notably the ones on p. 3 (our Figure 3) and p. 10. Figure 3 displays the 9:7 ratio obtained when, to quote the figure legend, “The character, colour for example, appears only when C and R meet.” We consider the more complex figure on p. 10 in a moment. Figure 3 was repeated by Lock (1906, p. 199) in his book Recent Progress in the Study of Variation, Heredity, and Evolution, the Preface being dated October 23. It will be noted that these squares are formed by the simple process of laying out the four gametotypes CR, cR, Cr, cr as headings for both rows (paternal gametes, say) and columns (maternal gametes) and “adding” them to create the entries in the squares corresponding to the zygotes formed by their unions.
However, when Punnett published the second edition of his Mendelism, he used a slightly different format (our Figure 2; Punnett 1907, p. 45) also displaying 9:3:3:1. It is divided into four large squares each of which contains four small squares. Each large square is identical in respect to the second locus, B,b, and shows the two types of gamete uniting to form zygotes, two of which, Bb and bB, are identical if gametic origin is ignored. The four large squares do the same for the first locus A,a, and then the four small squares for B,b are added to each of the large squares for A,a. Of course it comes to the same thing as Figure 3, the difference being only a matter of the labeling. In the third edition (Punnett 1911, p. 34) he reverted to the arrangement of Figure 3 complete with a description of the construction of what he called the “chessboard” method (although in truth it is more like a multiplication table).
When three loci are involved, an 8 × 8 square results, as given in Report III on p. 10 (Figure 4). This is an extremely interesting construction. Thinking of it as four large squares, we see that in respect to B,b and R,r, each of these squares is the same, but different from either of the methods of constructing a two-locus table so far described (in fact there is an error in columns 7 and 8, where the lower entries in row 5 have been interchanged). Instead of the union of gametes we have the union of loci, the rows for R,r, and the columns for B,b. Then each of these squares has been dropped into a square for C,c as in Punnett’s (1907) construction (Figure 2). This hybrid format was suggested by Sir Francis Galton in a letter to Bateson dated October 1, 1905 containing the original of Figure 4 (reproduced in Edwards 2012). It is odd that when it was published, in Report III and later, Galton’s help was not acknowledged.
Galton’s three-locus square from Report III (Bateson et al. 1906b).
To appreciate the significance of Galton’s arrangement it is necessary to describe the situation that confronted Bateson and Punnett, and since the experiments involved are the very ones that led to the discovery of partial coupling, this serves as an introduction to the next section. “The work was begun,” wrote Bateson in his book Mendel’s Principles of Heredity (Bateson 1909, p. 89), “by crossing two white sweet peas belonging to the variety Emily Henderson. These plants were alike in every respect so far as could be perceived, excepting that the shapes of the pollen grains differed, the one having the normal long pollen grains of the species, while the other had roundish grains. The object of the experiment was to trace the descent of the pollen-character and at the beginning no question of colour was entertained. When F1 was grown however it was clear that here was a remarkable opportunity of studying a reversion in color due to crossing, for these plants instead of being white were purple like the wild Sicilian plant from which our cultivated sweet peas are descended.”
Proceeding to the F2, Bateson and Punnett found “phenomena [which] … presented superficially an appearance of great complexity. … It is unnecessary to go through the long series of steps by which the analysis of the phenomena was carried out. The meaning of the facts is now perfectly clear and they can all be arranged in one consistent scheme” (Bateson 1909, p. 90). They worked out that three loci would do. The two original whites were CCrrBB and ccRRbb, leading to F1 all CcRrBb. On selfing, these would lead to the 64 combinations shown in Figure 4. In the presence of C (for color?) the situation is always that R (red) dominant to r gives a red flower to which B (blue) dominant to b adds blue to make a purple flower, although in the absence of R there is no blue alone. This is then the pattern in the three large squares corresponding to CC, Cc, and cC. In the fourth, cc, no colors of any kind appear. We end up with 3 × 9 = 27 purples, 3 × 3 = 9 reds, and 3 × 4 + 16 = 28 whites. The numbers given in Report III are 1634, 498, and 1593, respectively, 3725 in all, against expectations of 1571, 524, and 1630 (χ2 on 2 d.f. = 4.59, P = 0.10; all values of χ2 quoted here are newly calculated).
Partial Coupling (Linkage)
It is frequently said that linkage was discovered by Bateson and Punnett in 1905. Thus A. H. Sturtevant himself, writing A History of Genetics in retirement (Sturtevant 1965), records (p. 40) that “Incomplete linkage was first reported in the sweet pea by Bateson and Punnett (1905),” but already some qualifications are needed. First, “in the sweet pea” needs to be in parentheses, or at least between commas, because this was the first report of partial linkage in any organism. Second, the reference is actually to Bateson et al. (1905), as given by Sturtevant in his bibliography, which raises the question of the contribution of Saunders. (Morgan 1928, in The Theory of the Gene, p. 323, went further and omitted Saunders from the reference too.) Third, the word linkage in its genetical context had not, in 1905, been coined and is associated with the chromosomal theory advanced by Morgan (1911), who even then still used the term “coupling.” The first use of linkage in this connection is in 1912 (Morgan and Lynch 1912), but we should note that Bateson (1906) had written “We have proof that in certain cases a character, say of shape, may be so linked or coupled with another character, say of color, that all or a majority of the germs [gametes] which carry the one carry the other also.” Punnett (1911, p. 87), in the third edition of his Mendelism, wrote “In some way or other the factors for blue and for long pollen become linked together in the cell divisions that give rise to the gametes, but the linking is not complete.”
In the present account I use coupling for the statistical evidence as opposed to its chromosomal explanation, and, like Bateson and Punnett, I distinguish between complete coupling and partial coupling. This distinction is important, because complete coupling had already been found by Correns (1900) in stocks (Matthiola) as noted by Bateson and Saunders (1902), who reported similar “correlation” in their own experiments with stocks. Correns had used the word “gekoppelte.” Although this 1902 Report to the Evolution Committee of the Royal Society (Bateson and Saunders 1902) was the joint work of Bateson and E. Rebecca Saunders (“Becky”), Part I, in which the correlation was noted, is headed “Experiments with Plants, carried out by E. R. Saunders,” to whom therefore we may attribute the observation.
Partial coupling appears for the first time in Report II to the Evolution Committee (Bateson et al. 1905; received May 18, 1904), the one to which Sturtevant referred. It contains no further reference to correlation in its Matthiola section, but in the section on sweet peas we read “There is, therefore, some coupling of pollen-shape and colors” (italics original) (Bateson et al. 1905, p. 89). This section is headed “Experiments carried out by W. Bateson, E. R. Saunders, and R. C. Punnett (in 1904).” It is evident that many additions to Report II were made after May 1904, including a “Note added December 1904” at the end. The earliest mention of disturbed segregations corresponding to this coupling is in Bateson’s Report to the Committee on Experimental Studies in the Physiology of Heredity at the British Association meeting in Cambridge in August 1904 (Bateson 1905) and his Presidential Address to the Zoological Section at the meeting (also reproduced in Bateson 1928; the mention is on p. 255).
Then in Report III (Bateson et al. 1906b; received March 16, 1906) there is a full section on “Gametic Coupling,” which starts “Early in the revival of breeding experiments, attention was called, especially by Correns, to the phenomenon of coupling between characters. .... Examples of partial coupling have not hitherto been adequately studied. A remarkable case occurs in regard to the distribution of the pollen-characters in F2 from the white long x white round Sweet Pea” (Bateson et al. 1906b, p. 9), and the results are printed. More information is given in the later section of Report III devoted to the sweet pea itself (“Experiments by W. Bateson, E. R. Saunders and R. C. Punnett”). The crucial results had in fact appeared earlier in a brief note in Proceedings of the Royal Society, Series B (Bateson et al. 1906a; received December 1 and read December 7, 1905).
Finally, Report IV (Bateson et al. 1908) contains, in its introduction, a brief review of work on partial coupling, which starts “The majority of our Sweet Pea work of the past two seasons was undertaken with a view to further elucidating the phenomenon we have termed gametic coupling” (Bateson et al. 1908, p. 2). The section on sweet peas is headed “Experiments by W. Bateson and R. C. Punnett” and contains a subsection “Partial Gametic Coupling.”
There is some slight evidence that Sturtevant, in his History, might knowingly have credited this discovery of partial coupling to Bateson and Punnett, omitting Saunders. Although Saunders was the undoubted Queen of Matthiola, Punnett does seem to have been King of L. odoratus. Sturtevant (1965, Author’s Preface, p. xi) had “some direct personal contact” with Bateson and Punnett and had met Saunders, although she counted among those he “never really knew.” Bateson (1906), when discussing color in the sweet pea, refers to “an elaborate series of experiments made by Miss Saunders, Mr. Punnett, and myself,” but in the corresponding part of his book Mendel’s Principles of Heredity (Bateson 1909, p. 89) he refers to experiments as having been “carried on jointly by Mr. Punnett and myself for some years.” Nor is there any sense that he is inclined to neglect Saunders’ work, for the next section (Bateson 1909, p. 95) on “Colors of Stocks” (Matthiola) starts “The experiments of Miss E. R. Saunders have revealed ... .” For further information about Saunders see Richmond (2001, 2006) and references therein. Lock (1906, p. 200), a member of Bateson’s group at the time, says firmly “This phenomenon of partial gametic coupling was discovered by Bateson and Punnett in the Sweet Pea.” Punnett (1914) himself was characteristically self-effacing: “Bateson in 1905 was the first to describe in sweet-peas a remarkable case in which two characters each exhibiting ordinary Mendelian segregation nevertheless showed a peculiar distribution with regard to one another.” Report II refers to “the original crosses of 1901.” Punnett joined the sweet-pea work in 1904, growing the F2 in which he and Bateson noted the disturbed segregations, so the F1 must have been 1903, which would make the original cross 1902. Perhaps there were some in both 1901 and 1902.
In his reminiscences “Early days of genetics” given at the hundredth meeting of the Genetical Society at Cambridge in 1949, Punnett (1950) said “Sweet peas were the other main line of inquiry. We grew some thousands each year and of course the garden at Merton House [the Bateson home in Grantchester] could not nearly accommodate such numbers.” He goes on to describe the additional plots on the University Farm at Impington, four miles away, and the ride there “for a long afternoon, Bateson with his wife in the trailer carrying the ‘Farm Book’ and a microscope.” “One of us pulled the plant and sung out its characters and handed the plant to the other, who, with the microscope perched on some odd box picked up at the farm, determined the shape of the pollen. All duly logged by Mrs. Bateson” (Punnett 1950).
The “Farm Books” and allied notebooks recording experimental data are preserved in Cambridge University Library and might provide further information about the participants, if only by the handwriting. But no doubt they all helped each other, and it looks as though Mrs. Bateson deserved a formal mention too.
Bateson and Punnett found an F2 segregation 2844 long pollen and 881 round, against 3:1 expectations of 2794 and 931, respectively (χ2 on 1 d.f. = 3.62, P = 0.057). As we have seen, in the field they scored the color before the pollen type so it would be natural to have three columns for the colors, each divided into two for the pollen type, and this is how the data were presented in Report III (Table 1). They noted that the 3:1 ratio did not hold for the three color types individually. There seemed to be some kind of coupling of round with red and long with purple that was disturbing the Mendelian segregations; white seemed to be unaffected. Bateson and Punnett’s explanation was that B (blue) and L (for long) tended to associate in the gametes, as did their recessive counterparts b and l (round). The converse to this coupling was the “repulsion” of B and l, b and L.
F2 segregation in the sweet pea for flower color and pollen type
They were familiar with Mendel’s law of independent segregation and with the complete coupling reported by Correns and by Saunders, but here was something in between, partial coupling. “The significance of such partial coupling is obscure, and it may result from several processes, between which no discrimination can yet be made” (Bateson et al. 1906b, p. 9) (Report III). But it could be measured, and Bateson and Punnett found that if gametes were produced in the ratio 7BL:1Bl:1bL:7bl, the resulting phenotypic ratio 177BL:15Bl:15bL:49bl fitted the observed numbers (Table 1) quite nicely. The calculation of the phenotypic ratio from the gametic for an F2 segregation is now an elementary student exercise, but Report III did not explain it, and neither did Bateson (1909) in his book. The general result for the gametic ratio
was given in Report IV (Bateson et al. 1908) and by Punnett in the third edition of Mendelism, with a full explanation for the above case (Punnett 1911, Appendix to Chap. IX, p. 88):
(In fact, Punnett has a sign wrong in the gametic ratio.) Following Bridges (1914), nowadays we would use the recombination fraction θ = 1/n with the gametic ratio
to give the familiar
Alas, it did not occur to Bateson and Punnett that the “several processes” they could contemplate for the explanation of partial coupling need not be limited to integral values of n, and they became fixated on the further idea that n had to be a power of 2 [“pure numerology brought about by a fixation on Mendelian ratios” (Edwards 1996)], for they began to visualize processes of gametogenesis that required this as an explanation, their so-called “reduplication” hypothesis (Bateson and Punnett 1911; see below). If they had kept an open mind and allowed any value of n, or better still worked with the simpler θ, they would have been free to choose the best value without restriction. As late as March 1911, the date of the Preface to his third edition of Mendelism, Punnett writes (Punnett 1911, p. 87) “Nor for the present can we suggest why certain factors should be linked together in the peculiar way that we have reason to suppose that they are during the process of the formation of the gametes.”
Weldon (1902) had already applied Karl Pearson’s goodness-of-fit test to Mendel’s data, so that Bateson and Punnett could have chosen the value that gave the best fit by the criterion of χ2, thereby inventing the method of minimum χ2 nearly a decade before Engledow and Yule (1914) did so (reprinted with a commentary by Edwards 1997). But that would have been stealing the biometricians’ clothes.
We conclude by noting that Punnett made a very prescient remark about partial coupling when addressing the Epidemiological Section of the Royal Society of Medicine on February 28, 1908, 3 years before Morgan’s chromosomal linkage theory. “Enough, however, is known to make it certain that it [partial coupling] often plays an important part in heredity, and I have laid some stress upon it because it may eventually be found to throw light upon the alleged association of certain physical peculiarities in man with particular forms of disease” (Punnett 1908). The comment foreshadows the suggestion by Fisher (1935) in “Linkage studies and the prognosis of hereditary ailments” read to the International Congress on Life Assurance Medicine (see Edwards 2004, for Haldane’s possible contribution), which in turn foreshadowed the similar suggestion by J. H. Edwards (Edwards 1956) in connection with detecting marker loci in amniotic cells. For if a disease gene is linked closely enough to a marker locus, knowledge of the marker genotype may help in the prognosis of a disease not yet manifest. Punnett also remarked, in 1907 (Mendelism; Punnett 1907, p. 64), that “there is every probability that, as it [partial coupling] becomes better known, it will be found of peculiar importance in the elucidation of the architecture of the gamete.” In his last edition (Punnett 1927, p. 135) he reminded us of this by quoting it, adding “How brilliantly this prediction has been fulfilled by Professor Morgan and his colleagues will appear in the following chapter [the chromosome theory].”
The Reduplication Hypothesis
For many years neither Bateson nor Punnett accepted the chromosomal explanation of linkage, and by “coupling” and “repulsion” they meant statistical associations as observed in the sweet pea. In a talk in 1959 Punnett said “I have sometimes been asked how it was that having got so far we managed to miss the tie-up of linkage phenomena with the chromosomes. The answer is Boveri. We were deeply impressed by his paper ‘On the Individuality of the Chromosomes’ and felt that any tampering with them by way of breakage and recombination was forbidden” (Punnett 1950). In 1911 they advanced their “reduplication” hypothesis to explain coupling and its mirror phenomenon, repulsion. Its origin can be seen in some comments by Bateson in Mendel’s Principles of Heredity (1909, pp.157–161), but the definitive account is in Bateson and Punnett (1911). By the time Whitehouse (1965) wrote his magisterial Toward an Understanding of the Mechanism of Heredity it had been forgotten. We use Sturtevant’s (1965) historical account:
According to the reduplication hypothesis, segregation does not occur at the time of meiosis but somewhat earlier, and not necessarily at the same time for each pair of genes. The cells that are finally produced, each with a single set of genes, then multiply at different rates to give the observed ratios. It is not easy to see why this scheme was developed, since there is nothing in it that seems related to the (2n–1):1 series, nor is there any independent evidence for the complex and symmetrical pattern of divisions that it requires. The hypothesis is related to Bateson’s reluctance to believe that segregation occurs at the meiotic divisions (Sturtevant 1965, p. 40).
Sturtevant continues with further comments on Bateson’s thinking. For more information about the hypothesis and Bateson’s reluctance to accept the chromosome theory see Cock (1983), who, interestingly, headed his section on it “Bateson’s own rival theory,” and Cock and Forsdyke (2008). The best that can be said for the theory is that it seems to have spurred Morgan on to have his eureka moment in 1911 with the chromosomal explanation of linkage.
Punnett himself never incorporated reduplication into the later editions of his Mendelism, limiting his discussion to observations on the numerical ratios thought to be occurring. He pursued the question with further experiments in sweet peas (Punnett 1913, 1917a), but by the second of these articles he was already considering Morgan’s explanation of linkage, and in the fifth edition of Mendelism (Punnett 1919, p. 133) he introduced a new chapter, “The Chromosome Theory” “to present the position of the supporters of the chromosome theory ... [which] is, at the present moment, the most keenly discussed question in heredity.” But the controversy was not really being discussed any more, and one senses that his heart was not in reduplication and he simply did not want to upset Bateson.
Bateson (1922) famously abandoned his doubts “after a week in close communion with the wonders of Columbia University” visiting Morgan’s laboratory. The observations of the Belgian cytologist F. A. Janssens published in 1909 had persuaded Morgan and most other people of the existence of crossing-over sufficient to account for the observed linkage phenomena, even though doubt remained about Janssens’ precise model (see the Perspectives by Koszul et al., 2012, in GENETICS, Vol. 191, Num. 2). Morgan was to write, in The Theory of the Gene (Morgan 1928, p. 41) “From the nature of the case it is practically impossible to demonstrate, even when twisting of the chromosomes is admitted, that it actually leads to an interchange of the kind demanded by the genetic evidence.”
What did Punnett really think? According to Cock (1983) “At no time did Punnett show any great interest in chromosomes,” and I suspect that Punnett, who possessed “a blithe, kindly, open-air personality” (Needham 1967) quite unlike the combative Bateson, might simply have opted for a quiet life. Cock (1983) continued “He is unlikely, therefore, to have given Bateson any stimulus toward a more favorable view of chromosome theory.” There is also the possibility that he was sensitive to the view of his friend Lock, who had suggested as early as 1906 (Lock 1906, p. 252) that coupling might be due to “some mechanism which causes the representative particles of the respective characters concerned to remain in company during the process by which the other allelomorphs are being reassorted between the chromosomes,” as had been noted by Morgan and his colleagues (Sturtevant 1965). Even when describing the zygotic ratios arising from gametic coupling in his 1919 edition of Mendelism, Punnett (1919, p. 124) does not describe the reduplication hypothesis, merely saying “More recently the term ‘reduplication’ has been brought into use. …. The term is not altogether satisfactory, for biologists are not at present in agreement as to the manner in which these gametic series come to be formed.” Torn between Bateson and Lock, it would have been charactistic of Punnett to have kept his head down, and in any case from 1911 Bateson was at the John Innes Institute and not in Cambridge.
The Arthur Balfour Professorship of Genetics
The prehistory of the Arthur Balfour Professorship starts not with Punnett, but with Bateson, whom the University made a Reader in 1908. In their Report the recommending body, the General Board, had said that “they regret that in view of the state of University finances they cannot propose at the present time to establish a Professorship in Heredity and Variation” (Cambridge University Reporter 1907–1908, p. 213). The academic and political background to this appointment is fully described by Cock and Forsdyke (2008, p. 303). Evidently wheels were turning behind the scenes, for on February 24, 1908 the University’s Council was able to publish a report “on a proposed Professorship of Biology” (Cambridge University Reporter 1907–1908, p. 632; reprinted in part in Cock and Forsdyke, p. 306). An anonymous benefactor, likely to have been Arthur Balfour, had offered to support in part a Professorship to be devoted to “that branch of Biology now entitled Genetics (Heredity and Variation)” for 5 years in connection with the celebration of the Darwin centenary in 1909. Indeed, he wanted it to be the “Darwin Professorship,” but the Council thought a title should wait until “the professorship can … be placed on a permanent footing.” The duty of the Professor was quite specific: “to promote by teaching and research the knowledge of Genetics.” It was less than 3 years since Bateson had coined the word. The Professorship was clearly intended for him, and his election was announced on June 8. He gave his Inaugural Lecture “The Methods and Scope of Genetics” on October 23 (Bateson 1908) and it is from 1908 that Cambridge’s Professorship of Genetics really dates. For Punnett the “musical chairs” of posts led to the changes already mentioned in the biographical section above, culminating in his election to this Professorship of Biology when Bateson resigned it to take up the Directorship of the new John Innes Horticultural Institute in 1910.
Arthur James Balfour (1848–1930) was Prime Minister from 1902 to 1905, a brilliant aristocratic intellectual who held a key position in the Conservative party for nearly fifty years. He was the elder brother of Francis Balfour, who had lost his life in a climbing accident in 1882 soon after becoming Cambridge’s Professor of Animal Morphology. He had taught the undergraduate Bateson. Arthur Balfour’s many connections included his brother-in-law Lord Rayleigh, Chancellor of the University at the time of the Darwin Centenary, an office to which he himself succeeded in 1919. He was President of the British Association at the time of the 1904 Cambridge meeting and the foundation President of the Genetical Society in 1919, being succeeded on his death by Punnett. Among his undergraduate friends he counted George Darwin, with whom he played real (“court”) tennis, and George had taken him to visit his father Charles Darwin at his house in Downe, Kent. “The kindness of the great man, his sympathy and charm, exceeded all that could be demanded by the most self-centered guest, and left a deep impression on my youthful mind” (Balfour 1930, p. 38). Bateson could not have had a more powerful friend at court than Arthur Balfour.
During the 1909 Cambridge Darwin celebrations Balfour was chosen to propose Darwin’s “immortal memory” at the banquet on June 23. That morning the Chancellor, Lord Rayleigh, had ended his address of welcome to the delegates by saying
During the last generation, Cambridge, especially since the time of Michael Foster, has been active in biological work. We have the men and the ideas, but the difficulty has always been lack of funds. At the present time it is desired, among other things, to establish a Chair of Genetics – a subject closely associated with the name of Darwin and of his relative Francis Galton, and of the greatest possible importance, whether it be regarded from the purely scientific or from the practical side. I should like to think that the interest aroused by this Celebration would have a practical outcome in better provision for the future cultivation, in his own University and that of his sons of the field wherein Darwin labored (Cambridge University Reporter 1908–1909, p. 1372).
The plea did not fall on deaf ears. In July 1910 Balfour wrote a short article dealing with the endowment of the study of Genetics in the University. Late in 1911 a meeting was held at Balfour’s house in London, as a result of which an anonymous benefactor placed in the hands of Balfour’s friend Viscount Esher the sum of £20,000 to endow a Professorship to be called the Balfour Professorship of Genetics (Cambridge University Reporter 1911–1912, p. 694). Regulations were drawn up, which stipulated that the initial appointment should be made by Balfour and the Prime Minister jointly. It was also decided that the title should be the Arthur Balfour Professorship to avoid confusion with Francis Balfour.
Balfour wrote to Bateson, inviting him to accept the Professorship, but Bateson, unwilling to return from his Directorship of the John Innes Institute, declined and suggested that Punnett “is in every way worthy to be appointed” (Cock and Forsdyke 2008, p.386). And so he was, on November 11, 1912, being formally admitted at the Congregation on November 22. Whittingehame Lodge, the Professor’s house, was presented to the University in 1914 by Viscount Esher and Arthur Balfour, by then an Earl.
Punnett’s legacy to Cambridge University as Professor was modest. When his successor R. A. Fisher was elected in 1943, he found no staff and no students, but the large house, Whittingehame Lodge, intended for his occupation. “With the coming of war, the house was let to tenants and the land plowed up by the War Agricultural Committee. The department ceased to exist” (Box 1978, p. 398). Fisher was able to live in Caius College, since his Fellowship had been renewed on his return to Cambridge. Between 1943 and his retirement in 1957 he used the house and garden to develop a small Department and start a third-year Natural Sciences Tripos subject, “Genetics.” Nowadays the Department thrives, and one valuable direct legacy of Punnett’s remains to this day: his collection of offprints and many of his books.
However, Punnett influenced the young Fisher, who was a student in Caius College in 1909–1913 during which time he helped to found the Cambridge University Eugenics Society, approaching Punnett, one of the dons who was a member of the national Society, to serve on its Council. Punnett gave a lecture at the second public meeting of the University Society on December 5, 1911. “The undergraduate committee of the Society found Punnett’s exposition of Mendelism so important that, at a meeting in Fisher’s rooms [in Caius] the following term, Fisher as chairman proposed that they should make it a rule that each academic year one paper be devoted to an elementary exposition of the principles of heredity, meaning, of course, Mendelism” (Mazumdar 1992, p. 99).
From 1920 to 1926 Fisher was a Fellow of Caius at the same time as Punnett and though not resident he would have met him frequently. It was Punnett who, with Karl Pearson, reported unfavorably for the Royal Society on Fisher’s (1918) famous article “The correlation between relatives on the supposition of Mendelian inheritance,” prompting Fisher to remark to W. F. Bodmer in 1956 “My 1918 paper was refereed by Pearson and Punnett, both of whom I later succeeded” [personal communication; see also Fisher's letter to C. S. Stock, November 18, 1943, replying to Stock’s letter congratulating him on election to the Arthur Balfour Professorship (Bennett 1983, p. 264)]. All things considered, Fisher did not have a high academic opinion of his predecessor. I give some of the reasons for this below. Punnett had gone to his Somerset retirement before Fisher returned to Caius, and although they overlapped as Fellows until Fisher died in 1962, Punnett did not return often and there is no corporate memory of their interaction when he did.
The story of Punnett’s friendship with the mathematician G. H. Hardy and how it led to Hardy’s 1908 discovery of “Hardy–Weinberg equilibrium” at the same time as W. Weinberg’s has often been told, not always correctly. In itself it reveals little of Punnett except that he was puzzled by something that really is extremely simple, and he had to get Hardy to set him straight. The fullest and, I hope, most accurate, account is to be found in a recent Perspectives (Edwards 2008).
Later, when writing his book Mimicry in Butterflies, Punnett (1915) appealed to Hardy for some more mathematical help. He wanted to know the effects of selection at a single Mendelian diallelic locus under random mating, and Hardy, perhaps aware of the amount of computation involved, passed the problem on to his Trinity pupil H. T. J. Norton. The results were published in tabular form in Appendix I of Punnett’s (1915) book (and reprinted in Provine 1971). They were very influential, among other things inspiring J. B. S. Haldane to initiate his long series of articles on selection. Haldane was appointed Reader in Biochemistry at Cambridge in 1923, with a Fellowship of Trinity, and wrote that in 1922 Norton had shown him some calculations that were eventually published in 1928 (Haldane 1927; Norton 1928). Provine (1971) may be consulted for further details and Charlesworth (1980) for details of “Norton’s theorem.”
In 1917 Punnett again sought Hardy’s help over a similar problem, and this time Hardy himself calculated how slowly a recessive lethal is eliminated from a population, thus apparently discrediting the eugenicists’ claim that deleterious recessives could be eliminated in a few generations (Punnett 1917b). However, Fisher (1924) countered that these calculations “have led to a widespread misapprehension of the effectiveness of selection.”
Punnett (1930a) reviewed The Genetical Theory of Natural Selection (Fisher 1930a) for Nature. It was not friendly. Fisher (1930b) replied in a letter to Nature, to which the editor allowed Punnett (1930b) an immediate rejoinder. We now know, what Fisher could not have known at the time, exactly what Punnett reported to the Royal Society about Fisher’s “1918” article (Norton and Pearson 1976): “I have had another go at this paper but frankly I do not follow it owing to my ignorance of mathematics.” He ended “I do not feel that this kind of work affects us biologists much at present. It is too much of the order of problem that deals with weightless elephants upon frictionless surfaces, where at the same time we are largely ignorant of the other properties of the said elephants and surfaces.” It was not to be expected that a man of such opinion would, only a dozen years later, be able to offer an informed assessment of The Genetical Theory, and Punnett seemed to admit as such: “Probably most geneticists to-day are somewhat skeptical as to the value of the mathematical treatment of their problems. With the deepest respect, and even awe, for that association of complex symbols and human genius that can bring a universe to heel, they are nevertheless content to let it stand at that, believing that in their own particular line it is, after all, plodding that does it.” Leonard Darwin wrote to Fisher “I am rather sorry they picked out an old discontinuous stick-in-the-mud like Punnett to review you in Nature. But to get 5 columns is an excellent advertisement. My father would have been much pleased with such a review of the Origin, and merely carefully noted the points to answer in his next edition. I think you may be well pleased. I never had so long a review” (Bennett 1983, p. 131).
In the review Punnett advanced his mutationist position: “Throughout the book one gets the impression that Dr. Fisher views the evolutionary process as a very gradual, almost impalpable one, in spite of the discontinuous basis upon which it works.” He touches on melanic moths, on poultry, and on mimicry, subjects on which he was well informed as a naturalist, and ends up by complaining about Fisher’s English. Bennett (1983, p. 35) reports that the review “was a great disappointment to Fisher,” but one wonders whether the disappointment was more over the choice of reviewer than the content, because Fisher knew Punnett well enough not to have expected anything else from him. Fisher’s response listed six points (“misstatements or other slighter misrepresentations”), and Punnett attempted to answer them. The exchange served only to emphasize the magnitude of the scientific gulf that separated the first two holders of the Arthur Balfour Professorship of Genetics.
Reginald Crundall Punnett owed his academic career and reputation to the good fortune of being invited by William Bateson to join him as his partner in undertaking breeding experiments in both plants and animals in the heady days that followed the rediscovery and appreciation of Mendel’s article at the beginning of the 20th century. Having made a signal contribution to these studies his good fortune continued when he found himself the natural alternative to Bateson to occupy the Arthur Balfour Professorship of Genetics at Cambridge when Bateson declined it. Thereafter he lived the comfortable life of a Professor between the wars, provided with a house by the University, a Fellowship by his College, and the absence of pressing duties by either.
But one should not belittle the diagram that bears his name, any more than one should belittle Venn’s famous logic diagram, just because it is simple. It served a need so well that it is difficult to see how the complex pattern of inheritance of flower color in the sweet pea could have been unraveled without it. The discovery of partial linkage depended on the knowledge thus gained. Bateson (1909, p. viii) wrote “In 1904 I had the good fortune to gain Mr. R. C. Punnett as a partner. Since that date we have worked in close collaboration, and the work that we have thus done has been in every sense a joint product, both as regards design, execution, and interpretation of results.” But he was careful to attribute the diagram to Punnett, as we have noted.
G. Evelyn Hutchinson (Hutchinson 1979) remembered from his undergraduate days:
Genetics was taught twice a week, at five o’clock in the Michaelmas term, by R. C. Punnett … . He was a mild man with an overdominant wife who had been a major tennis player. Her opponents must have been terrified. Punnett had fine collections of Chinese porcelain and Japanese prints in a delightful house backed by an experimental garden, and he devoted himself largely to the genetics of sweet peas. The Punnetts gave Sunday lunches with superb wine to an incongruous set of students, half biological intellectuals, half athletes, all I think men. Only about half a dozen students took Punnett’s course. … The chromosome theory was still widely debated. Bateson was usually skeptical, though I know he accepted it for about a fortnight before his death. Punnett tended to be more receptive to the idea. One evening the high point of the course arrived unexpectedly; Punnett came in demurely and then announced that he had just finished all the calculations of linkage of the various characters he had studied in the sweet pea and that indeed there were as many linkage groups as chromosomes. The chromosome theory had worked for a plant as well as an animal and therefore might reasonably be expected to be of general validity (Hutchinson 1979, p. 99).
Punnett’s paper reporting this is Punnett (1923b).
But I leave the last word to Joseph Needham (Needham 1967), the Master of Caius: “Punnett also had a highly scholarly side, being greatly interested in the history of biology and possessing a notable library of its seventeenth and eighteenth-century literature. Unfailingly helpful and charming to younger colleagues, he would present them sometimes with rare books, and encourage them in their work in ways which they could never hope to repay. We greatly cherish his memory and record this for the information of later generations.”
I am grateful to Peter O’Donald for the reference to Hutchinson (1979) and to Axel Zeitler for help in understanding Correns (1900).
- Balfour A. J., 1930. Chapters of Autobiography, edited by Dugdale E., editor. Cassell, London
- Bateson, B., 1928 William Bateson, Naturalist. Cambridge University Press. Reprinted in Cambridge Library Collection, Cambridge University Press, 2009, Cambridge/London/New York.
- Bateson, W., 1905 Report of the 74th meeting of the British Association for the Advancement of Science, Cambridge, August 1904. Murray, London.
- Bateson, W., 1906 An address on Mendelian heredity and its application to Man. Brain 29: 157–179. Reprinted in Bateson, B. (1928, pp. 181–200)
- Bateson, W., 1908 The Methods and Scope of Genetics. Cambridge University Press, Cambridge/London/New York. Reprinted in Bateson, B. (1928, pp. 317–333)
- Bateson, W., 1909 Mendel’s Principles of Heredity. Cambridge University Press, Cambridge/London/New York.
- Bateson, W., 1922 Evolutionary faith and modern doubts. Science 55: 55–61 and Nature 109: 553–556. Reprinted in Bateson, B. (1928, 389–398)
- Bateson W., Punnett R. C., 1905; see, Bateson, Saunders and Punnett; (1905)
- Bateson W., Punnett R. C., 1911. On gametic series involving reduplication of certain terms. J. Genet.1: 293–302
- Bateson W., Saunders E. R., 1902. Experimental Studies in the Physiology of Heredity (Reports to the Evolution Committee of the Royal Society, Report I), pp. 3–160
- Bateson W., Saunders E. R., Punnett R. C., 1905. Experimental Studies in the Physiology of Heredity (Reports to the Evolution Committee of the Royal Society, Report II), pp. 4–99
- Bateson W., Saunders E. R., Punnett R. C., 1906a Further experiments on inheritance in sweet peas and stocks: preliminary account. Proc. R. Soc. Lond., B77: 236–238
- Bateson W., Saunders E. R., Punnett R. C., 1906b Experimental Studies in the Physiology of Heredity (Reports to the Evolution Committee of the Royal Society, Report III), pp. 2–53
- Bateson W., Saunders E. R., Punnett R. C., 1908. Experimental Studies in the Physiology of Heredity (Reports to the Evolution Committee of the Royal Society, Report IV), pp. 2–18
- Bennett J. H., editor. (Editor), 1983. Natural Selection, Heredity, and Eugenics. Including selected correspondence of R. A. Fisher with Leonard Darwin and others Clarendon Press, Oxford
- Bridges C. B., 1914. The chromosome hypothesis of linkage applied to cases in sweet peas and primula. Am. Nat.48: 524–534
- Box J. F., 1978. R. A. Fisher: The Life of a Scientist. Wiley, New York
- Charlesworth, B., 1980 Evolution in Age-Structured populations. Cambridge University Press, Cambridge/London/New York.
- Cock A. G., 1983. William Bateson’s rejection and eventual acceptance of chromosome theory. Ann. Sci.40: 19–59 [PubMed]
- Cock A. G., Forsdyke D. R., 2008. Treasure Your Exceptions: The Science and Life of William Bateson. Springer-Verlag, New York
- Correns C., 1900. Ueber Levkojenbastarde. Botanisches Centralblatt84: 97–113
- Crew F. A. E., 1967. Reginald Crundall Punnett. Biogr. Mem. Fellows R. Soc.13: 309–326
- Crew F. A. E., 1968. R. C. Punnett. Genetics58: 1–7 [PubMed]
- Edwards A. W. F., 1958. An analysis of Geissler’s data on the human sex ratio. Ann. Hum. Genet.23: 6–15 [PubMed]
- Edwards A. W. F., 1996. The early history of the statistical estimation of linkage. Ann. Hum. Genet.60: 237–249 [PubMed]
- Edwards A. W. F., 1997. Three early papers on efficient parametric estimation. Stat. Sci.12: 35–47
- Edwards A. W. F., 2004. Mendelism and man 1918–1939, pp. 33–46 A Century of Mendelism in Human Genetics, edited by Keynes M., Edwards A. W. F., Peel R., editors. CRC Press, Boca Raton, FL
- Edwards, A. W. F., 2008 G. H. Hardy (1908) and Hardy–Weinberg equilibrium. Genetics 179: 1143–1150. [PMC free article][PubMed]
- Edwards A. W. F., 2012. Punnett’s square. Stud. Hist. Philos. Biol. Biomed. Sci.43: 219–224 [PubMed]
- Edwards J. H., 1956. Antenatal detection of hereditary disorders. Lancet270: 579
- Engledow F. L., Yule G. U., 1914. The determination of the best value of the coupling-ratio from a given set of data. Proc. Camb. Philos. Soc.17: 436–440
- Fisher R. A., 1918. The correlation between relatives on the supposition of Mendelian inheritance. Trans. R. Soc. Edinb.52: 399–433
- Fisher R. A., 1924. The elimination of mental defect. Eugen. Rev.16: 114–116 [PMC free article][PubMed]
- Fisher R. A., 1927. On some objections to mimicry theory: statistical and genetic. Trans. R. Entomol. Soc. Lond.75: 269–278
- Fisher, R. A., 1930a The Genetical Theory of Natural Selection. Clarendon Press, Oxford. Ed. 2, Dover, New York (1958); variorum edition, Oxford University Press, Oxford (1999)
- Fisher R. A., 1930b Genetics, mathematics, and natural selection. Nature126: 805–806
- Fisher, R. A., 1935 Linkage studies and the prognosis of hereditary ailments. Transactions of the International Congress on Life Assurance Medicine, London.
- Haldane, J. B. S., 1927 A mathematical theory of natural and artificial selection, Part IV. Proc. Camb. Philos. Soc. 23: 607–615. Reprinted in Weiss and Ballonoff (1975), pp. 98–106.
- Hutchinson G. E., 1979. The Kindly Fruits of the Earth: Recollections of an Embryo Ecologist. Yale University Press, New Haven, CT
- Koszul, R., M. Meselson, K. Van Doninck, J. Vandenhaute, and D. Zickler, 2012 The centenary of Janssens’s chiasmatype theory. Genetics 191: 309–317. [PMC free article][PubMed]
- Lock R. H., 1906. Recent Progress in the Study of Variation, Heredity, and Evolution. Murray, London
- Mazumdar P. M. H., 1992. Eugenics, Human Genetics, and Human Failings. Routledge, London
- Morgan T. H., 1911. Random segregation vs. coupling in Mendelian inheritance. Science 34: 384
- Morgan T. H., 1928. The Theory of the Gene, revised edition Yale University Press, New Haven, CT
- Morgan T. H., 1929. Bateson and Mendelism. Review of Punnett (1928). Nature124: 171–172
- Morgan T. H., Lynch C. J., 1912. The linkage of two factors in Drosophila that are not sex-linked. Biol. Bull.23: 174–182
- Needham, J., 1967 Reginald Crundall Punnett. The Caian, October 1967, pp. 43–44.
- Norton, H. T. J., 1928 Natural selection and Mendelian variation. Proc. Lond. Math. Soc. 28: 1–45. Reprinted in part in Weiss and Ballonoff (1975). pp. 107–131.
- Norton B., Pearson E. S., 1976. A note on the background to and refereeing of R. A. Fisher’s 1918 paper ‘The correlation between relatives on the supposition of Mendelian inheritance’. Notes Rec. R. Soc. Lond.31: 151–162 [PubMed]
- Provine, W. B., 1971 The Origins of Theoretical Population Genetics. Chicago University Press, Chicago.
- Punnett R. C., 1903. On nutrition and sex-determination in man. Proc. Camb. Philos. Soc.12: 262–276
- Punnett, R. C., 1905, 1907, 1911, 1919, 1927. Mendelism. Macmillan, London.
- Punnett R. C., 1908. Mendelism in relation to disease. Proc. R. Soc. Med.1: 135–168 [PMC free article][PubMed]
- Punnett R. C., 1913. Reduplication series in sweet peas. J. Genet.3: 77–103
- Punnett R. C., 1914. Mendelism in Great Britain. J. Hered.5: 86–89
- Punnett, R. C., 1915 Mimicry in Butterflies. Cambridge University Press, Cambridge/London/New York.
- Punnett R. C., 1917a Reduplication series in sweet peas II. J. Genet.6: 185–193
- Punnett R. C., 1917b Eliminating feeblemindedness. J. Hered.8: 464–465
- Punnett R. C., 1923a Heredity in Poultry. Macmillan, London
- Punnett R. C., 1923b Linkage in the sweet-pea (Lathyrus odoratus). J. Genet.13: 101–123
- Punnett R. C., 1926. William Bateson. Edinb. Rev.244: 71–86
- Punnett, R. C., ed., 1928 Scientific Papers of William Bateson, Vols. 1 and 2. Cambridge University Press, Cambridge/London/New York.
- Punnett R. C., 1930a Genetics, mathematics and natural selection: Review of Fisher (1930a). Nature126: 595–597
- Punnett, R. C., 1930b See Fisher (1930b)
- Punnett R. C., 1950. Early days of genetics. Heredity4: 1–10
- Punnett R. C., 1952. William Bateson and Mendel’s Principles of Heredity. Notes Rec. R. Soc. Lond.9: 336–347
- Richmond M. L., 2001. Women in the early history of genetics. Isis92: 55–90 [PubMed]
- Richmond M. L., 2006. The domestication of heredity: the familial organisation of geneticists at Cambridge University, 1895–1910. J. Hist. Biol.39: 565–605
- Sturtevant, A. H., 1965 A History of Genetics. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. (Cold Spring Harbor Laboratory Press/Electronic Scholarly Publishing Edition, 2000.)
- Weiss, K. M., and P. A. Ballonoff, 1975 Demographic Genetics (Benchmark Papers in Genetics 3). Dowden, Hutchinson and Ross, Stroudsburg, Pennsylvania.
- Weldon W. F. R., 1902. Mendel’s laws of alternative inheritance in peas. Biometrika1: 228–254
- Whitehouse H. L. K., 1965. Towards an Understanding of the Mechanism of Heredity. Arnold, London
Articles from Genetics are provided here courtesy of Genetics Society of America