596 



NATURE 



[January 6, 1921 



Letters to the Editor. 



\The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Heredity and Acquired Characters. 



(1) Most biologists believe that the heritage travels 

 down the germ-tract. (2) .Ml biologists believe that in 

 the germ-cell are none of the characters which the 

 individual afterwards develops, but only potentialities 

 for producing them in response to fitting nurture. 

 (3) It follows necessarily that only potentialities are 

 transmitted. (4) All that is transmitted is not pro- 

 duced (as characters of the individual), for fitting 

 nurture may be lacking. (5) Therefore, inheritance 

 and reproduction are not synonjmous terms. (6) The 

 individual can produce nothing but what was potential 

 in the germ-cell, and nothing except in response to fit- 

 ting nurture. (7) Necessarily, therefore, all characters 

 are innate, acquired, germinal, somatic, and inheritable 

 in exactly the same sense and degree. Given these facts 

 and inferences, I asked biologists why they described 

 some characters as "innate," "germinal," and "in- 

 heritable," and others as "acquired," "somatic," and 

 "non-inheritable." I gave the example of the head 

 and the scar, both ancient products of evolution. 

 Why, when the child is like his parent both by nature 

 and by nurture, is he said to inherit the head but not 

 the scar? Why is the word "inherit" used as 

 synonymous with "vary," its direct opposite, in the 

 case of the scar? Really, I was asking for such 

 definitions of biological terms as would accord with 

 the current usage of them. As yet I have got none. 

 I think I shall get none. 



I may be wrong in thinking that biological 

 terminology is vague, and sometimes even unmean- 

 ing, or I may be right. If I am wrong, surely some 

 biologist can give the definitions I ask for. If I am 

 right, the matter is of importance even as a mere 

 question of words. A science cannot progress unless 

 its workers have means of expressing themselves 

 precisely and clearly. Other interpretative sciences — 

 e.g. mathematics, physics, astronomy, and chemistry 

 — have such means. It is noteworthy that they all 

 possess in addition a body of established truth — truth 

 which no one who knows the facts disputes. But 

 biology can boast of scarcely an important interpreta- 

 tion (not even the theory of natural selection) which 

 is accepted by everyone. As in religion and politics, 

 its workers are divided into more or less hostile sects 

 and sub-sects — Lamarckians, Darwinians, Neo-Dar- 

 winians, Mendelians, mutationists, Mendelo-muta- 

 tionists, biometricians, and the like. I submit that 

 much of this extreme, and apparently irreconcilable, 

 divergency of opinion is due to confusion of thought 

 consequent on confusion of language. 



But beyond words, the matter is important. Bio- 

 logists classify characters as "innate " and "acquired." 

 Phvsiologists ignore this classification, and, assuming 

 that all characters develop in response to nurture, 

 endeavour to ascertain what forms of nurture evoke 

 them. In other words, they classify characters 

 according to the nurtures w-hich cause them to 

 develop — use, injury, this or that hormone, and the 

 like. This classification is not merely different from 

 the biological one ; it is actually antagonistic ; for, 

 of course, if all characters equally arise in response 

 to nurture, they must all equally take origin in ger- 

 minal potentiality — must be equally innate and 

 acquired. If biologists cannot justify their use of 

 NO. 2671, VOL. 106] 



terms (supply valid definitions), it appears to me that 

 they have no alternative but to accept the physio- 

 logical classification. If that be done, I conceive 

 that some such simple formula as "The sole ante- 

 cedent of non-inheritance is variation. Apart from 

 variations, like exactly begets like when parent and 

 child develop under like conditions," will almost 

 cover the field of discussion. 



In reply to Dr. Ruggles Gates's letter in Nature 

 of December 2, p. 440, if we believe with Darwin 

 in his theory of pangenesis that the parts of the child 

 are derived from the similar parts of the parent (the 

 child's head from the parent's head, etc.), the dis- 

 tinction between variations and modifications vanishes. 

 Every modification is then a variation. We can dis- 

 tinguish only between germinal and somatic varia- 

 tions. If we believe that modifications in the germ's 

 environment (the soma) may so impress the germ as 

 to cause variations, then I think we are accepting 

 what nobody questions, though I believe the import- 

 ance of variations so caused has been greatly e.xag- 

 i<erated. If we believe that changes in the .soma 

 tend to impress the germ-plasm in such a 

 remarkable and unlikely way that the child repro- 

 duces in response to a different stimulus the character 

 which the parent produced in response to the 

 stimulus that Nature had fitted his race to respond 

 to, then undoubtedly that child has varied from the 

 parent. He is of a different nature ; he has not in- 

 herited. I confess I do not see how Mendelians and 

 mutationists as such are concerned in this discus- 

 sion. They think that fluctuations are modifications, 

 and that only mutations are true variations, and, 

 therefore, that only the latter are inheritable— all of 

 which is at least intelligible. 



Prof. MacBride and Sir Ray Lankester (Nature, 

 December 16, pp. 500-1) may convenientlv be answered 

 together. But if, after reading what foUoVvs, Prof. 

 MacBride will precisely indicate the "quibble" he 

 writes of, I shall be much obliged. In reference to 

 his last paragraph, if the child of a parent with an 

 extra digit lacks that extra digit, or if he is relatively 

 fair, then he has varied from the parent, has he not? 

 Yet he has not departed from what is normal in the 

 species. Prof. MacBride tortures a word which has 

 nbw an established and perfectly clear meaning. 



In 1911-12 I instanced a scar as a so-called 

 •acquired character." Then, as now. Sir Ray 

 Lankester quoted Lamarck in the original French. 

 Lamarck wrote about the effects of use and disuse 

 (not about the effects of injury). Therefore, pace Sir 

 Ray Lankester, a scar is not an acquired character. 

 Therefore, " if you, without any warrant, alter the 

 established signification given by the Neo-Darwinian 

 to the chief term in his statement, you can, of course, 

 convert it into nonsense, and your proceeding is 

 merely farcical." It is as if I had asked whv 

 kippers were called whales and Sir Ray Lankester 

 had insisted that the term was restricted to red 

 herrings. Fortunately, I am in good company. Did 

 not Weismann himself cut off the tails of rats by 

 way of demonstrating that acquired characters were 

 not transmissible? If in my letter Sir Ray Lankester 

 substitutes any use-acquirements he likes for " scar," 

 his requirements will be met. In 1911-12 Sir Rav 

 Lankester declared I was "doing harm." Influenced, 

 doubtless, by the opinion of so great an authoritv, 

 the Exlitor closed the correspondence. Thus was I 

 crushed. The odd thing is that at the time I believed 

 — as I do now — that I was fighting my critic's — or 

 shall I say my contemner's — battles. We had travelled 

 by different roads, but had reached, as far as I could 

 judge, the same goal, and I was seeking to clear the 

 ground. But more of this anon. 



