December i6 1920] 



NATURE 



501 



Ucidats — that which is associated with the normal 

 form of the species. 



The " Lamarckian controversy " about which Sir 

 Archdall Reid affects to be ignorant was, and is, as 

 to whether the changes of structures set up in the 

 manner indicated in Lamarck's first law are ever 

 transmitted by generation to progeny. It has been 

 demonstrated that such changes do occur, but no 

 satisfactory evidence of their transmission by genera- 

 tion to progeny has been produced. It is admitted 

 that, so far as we know, such a transmission is 

 possible, and, in the period at which Lamarck wrote, 

 tfie assumption that such transmission occurs was a 

 reasonable one. But hitherto all attempts to give 

 ( onvincing demonstration of its occurrence have failed, 

 I hough such attempts have been, and still are, made 

 by able biologists. 



Before concluding this letter, may I direct the atten- 

 tion of readers of Nature to the correspondence on 

 this subject which was started by Sir Edward Fry in 

 1S94 (vol. li., p. 54), to which I contributed a long 

 -tatement? Sir Edward, owing to his lack of 

 I quaintancc with l^marck's writings, was genuinely 

 iiisled by the term "acquired characters," then less 

 familiar than it is to-day. E. Ray La.vkester. 



fJecember 8. 



In Nature of November 25 there appears a long 

 letter from Sir .Archdall Reid on the subject of 

 heredity. In this letter he seeks to show that 

 the whole controversy about the inheritability 

 of acquired characters — perhaps the controversy 

 of most vital importance in biology — is a mere 

 "pother" about "words full of sound and fury, signi- 

 fying nothing." ".Ml the characters of the indi- 

 vidual," he assures us, "are innate, acquired, and 

 inheritable in exactly the same sense and degree." 



Sir .\rchdall Reid must have a singularly poor 

 opinion of the intelligence of his co-workers in the 

 field of biology if he thinks that they have wasted, 

 and are still wasting, their time in a meaningless 

 controversy. The list of such "wasters," moreover, 

 must include the honoured name of Darwin himself, 

 who h.ad a very clear idea of what was implied in 

 the term "inheritance of acquired characters," only 

 he termed it the " inheritance of the effects of use and 

 disuse." 



The fart is that the whole of Sir Archdall Reid's 

 Ii^tter rests on a mere play with words. I recollect 

 n^ading of a lawyer who, in defending a client on a 

 I hargc of slander, maintained that "villain" was a 

 •rfertly harmless epithet, since logically and etymo- 

 igirally it only signified a servant employed on a 

 fnrm. 



Sir Archdall Reid begins by stating that all 

 I haraclcrs are acquired in response to external condi- 

 tions, since there are-no characters, but only potentiali- 

 ■ios, in the formless germ, and these potentialities will 

 '>t l)e realised unless conditions are favourable. Did 

 ,;, A,-, i„i-,|| Reid imagine that this was doubted by 

 ■;t? Is it not, on the contrarv. so elemen- 

 ■ If-evidrnt that everv biologist, in discussing 

 genetic questions and assumfng an irreducible mini- 

 mum of intelligence in his hearers, takes it for 

 rantJ'd ? 



If, however. Sir Archdall Reid thinks that such nn 

 assumption is unjustifiable, let me try to make the 

 issue fi little clearer. 



The egg of any animal will only develop its innate 

 possibilities as manifested in the features of the adult 

 animal if the surroundings are favourable, but the 

 development results in a definite type. If the sur- 

 roundings are unfavourable the type may not come 

 to fruition, but there will be an obvious attempt to 



NO. 2668, VOL. 106] 



attain it; the egg of the shrimp, for instance, never 

 shows any tendency to develop into the same form as 

 the egg of a fish. There is, of course, for every egg 

 a particular combination of circumstances which is 

 especially favourable and may be termed the normal 

 environment, and the normal life of the animal and 

 the function of its organs consist in answering 

 the demands made upon it by this environment. 



If, now, the environment be altered to such a 

 moderate extent that the animal is still able to respond 

 to it, then the use of certain of the animal's organs 

 and their growth will be altered. On that point all 

 iire agree<l ; the difference between opposing schools of 

 biologists begins when the question is raistd as to 

 what will be the characters of the offspring of the 

 altered individual. 



The Neo-Darwinian or Weismannian school main- 

 tains that the germs produced by the altered animal 

 will be precisely like the germ which gave rise to 

 that animal, if they develop in the normal environ, 

 ment of the species they will give rise to individuals 

 conforming to the normal specific type ; if they 

 develop in the same circumstances as their imme- 

 diate parent they will show similar divergences from 

 the specific type. 



The Lamarckian school, on the other hand, contends 

 that the germs of the altered animal become them- 

 selves slightly altered, so that if they are allowed to 

 develop in the normal specific environment they mav 

 still in their earlier stages of growth show a trace 

 of the altered structure of their parent ; and, on the 

 other hand, if they are allowed to develop in the 

 same circumstances as their parent thev will manifest 

 the altered structure acquired by the parent more 

 rapidly and in stronger degree than did the parent. 



I have already had occasion to direct the attention 

 of readers of N.^ture to the fact that certain experi- 

 menters on the Continent claim to have estab- 

 lished the truth of these two essential postulates of 

 Lamarckism. This claim may be ill-founded or well- 

 founded — that is a matter for argument — but no 

 reasonable Neo-Darwinian would fail to admit that if 

 the claim proves to he well-founded the lamarckian 

 position will be established. 



Sir -Archdall Reid states that, "apart from vaiia- 

 tion, like exactly begets like when parent and child 

 develop under like conditions." Leaving aside for 

 the moment the quibble about the word "variation," 

 the Lamarckian contention is that like docs not 

 "exactly beget like," but that the influence of condi- 

 tions on the character of the individuals composing a 

 species is cumtdative from generation to generation. 

 There is a rapidly accumulating body of evidence in 

 favour of this view ; for a piece of evidence to which 

 my attention has recently been directed I am indebted 

 to my friend and colleague, Prof. Dendy. It is as 

 follows : The peach in Europe is a deciduous tree. 

 Transplanted to Reunion it has become an evergreen 

 in the lowlands of that island, but has remained 

 deciduous in the highlands. If a seed be taken from 

 the evergreen tree and grown in the highlands it will 

 still in the first generation give rise to an evergreen 

 tree, although its ancestors wore undoubtedly 

 deciduous. 



Finally, I should like to say that the sense in which 

 I understand the word "variation," and the sense 

 in which I think it is understood bv the majority of 

 my co-workers, is a divergence from the normal 

 appearing among the offspring of n normal individual 

 when the normal environment remaitis unchanged. 

 and in that sense it should be used bv Sir Archdall 

 Reid. E. W. MacBridk. 



Imperial College of Science, .South Kensington, 

 London, S.W.7. December 8. 



