Commemoration of the publication of Gregor Mendel's pioneer experiments in genetics / Papers read at the Annual General Meeting, April 23, 1965.

  • American Philosophical Society
Date:
1965
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Commemoration of the publication of Gregor Mendel's pioneer experiments in genetics / Papers read at the Annual General Meeting, April 23, 1965. Source: Wellcome Collection.

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    VOL. 109, NO. 4, 1965] MENDEL, HIS WORK AND PLACE IN HISTORY 195 have got the idea from trial tests or pilot experi¬ ments not reported separately. But this seems unlikely in an investigator who reported results as fully and in as much detail as Mendel. There are no indications that he had got the essential idea from any of his botanical or horti¬ cultural predecessors.^ Kölreuter and Gärtner, to vi^hom he refers, worked with true species hy¬ brids differing in many variable intergrading char¬ acters from which such a rule as Mendel envisaged could not have been derived. Herbert, Lecoq, and Wichura, also cited by Mendel, had not reported their results in such a way that a binary rule like Mendel's could have been inferred from them. The work of those who came closest to Mendel's ob¬ servations was not mentioned by Mendel. At the time of the formulation of his principles he seems not to have known of the work of Goss or of Seton who in 1822 observed dominance and segregation of seed color in peas, but without numerical observations or interpretation. Charles Naudin, a French contemporary of Mendel, came close (in 1863) to views Mendel reached at the same time but his results were not reported in such a manner that, even had Mendel seen them, they could have served as origin or as tests of a sta¬ tistical theory. At present we shall have to assume that Mendel originated the idea of elements which could occur in the alternative states such as he represented symbolically as A (round seed form), a (wrinkled seed form), etc. His recognition of the binary behavior of such elements, A and a always split¬ ting in the hybrid A a to enter different gametes of which equal numbers were therefore produced, was clearly evident in his application to them of the binomial principle and the laws of combination based upon the assumption of integral character of elements. This kind of character or behavior had not heretofore been imputed to biological units al¬ though it had appeared in the laws of chemical combination based on stable elements. Barthelmess (1952: p. 76)^^ has made this interesting comment on Mendel's theory : This astonishing explanation could have become the basis for resolving the antithesis constancy—change- ableness : for it showed that the single traits were in fact constant, and segregated out again unaltered after a cross, while just as truly a change of character oc- 20 A careful account of the work of Mendel's prede¬ cessors is in : H. F. Roberts, Plant Hydridisation Before Mendel (Princeton, N. J., 1929), p. 323. Alfred Barthelmess, VererbungswissenschafOrbis Academicus (München, Verlag Karl Albers, 1952). curred in the descendants of a hybrid in which the same single traits appeared in different combinations. Indeed in this way even constant new combinations could arise. Constant elements, variable combina¬ tion was ready to ¡hand as a synthesis—exactly as it had been several decades earlier in chemistry. This manner of thinking in terms of recombin- able elements which was growing in chemistry during Mendel's school days may well have come to his mind again in 1851-1853 when he attended lectures in physics and chemistry at Vienna. It was shortly after this experience, in 1854, that he turned to observations on plants and noted the sharp differentiating characters occurring in different combinations in varieties of peas. Since there was no precedent for such an idea in bio¬ logy, it is not unreasonable to suggest, as Bar¬ thelmess has, that it may have come from chem¬ istry. There is one aspect of Mendel's scientific culture which has not attracted much attention but which should be considered when seeking sources for his theory. This was his training in and teaching of physics. It was his high school physics teacher, Friedrich Franz, who recommended him to the Monastery of St. Thomas, saying In my own branch, he is almost the best. ® This determined the course of his life. When Mendel himself came to teach, it was mathematics and Greek for the first year but thereafter, from 1854 to 1868, he taught physics and natural history. Even though he never qualified for a teaching certificate he appears to have been a successful teacher of physics. It is not clear to what extent his facility with mathematical reasoning which appears in his paper came from his experience in experimental and mathematical physics and there is no evidence to support speculation on this. But mathematics and the physical sciences seem more likely sources than the biological ones for the methods he applied so successfully to the study of inheritance. From whatever source Mendel got his central theory, it was unique in its time and remained so for thirty-five years. Mendel's scientific character may perhaps be brought into clearer focus by comparing him with some of his contemporaries. Darwin (born 1809) was thirteen years older than Mendel. His work had a scope and a sweep which contrasts sharply with Mendel's concen¬ tration on what seemed a restricted and delimited problem, that of the transmission mechanism of heredity. Darwin seldom resorted to counting but when he did, in observing snapdragons of two different colors in the second generation