500 



NATURE 



[December i6, 1920 



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. 



In his letter headed " Heredity " published in 

 Nature of November 25 Sir Arclidall Reid has not 

 done justice to himself or to your readers. He 

 endeavours to gain attention once more for a jocose 

 misrepresentation of the meaning of the term 

 "acquired characters," and in order to do so neglects 

 to mention the fact that in Nature, vols. Ixxxviii. and 

 Ixxxix. {191 1 and 1912), the matter was very fully 

 treated in letters from himself and others, including 

 two from me (vol. Ixxxix., p. 61 and p. 167). It 

 is the simple fact that in those volumes Sir Archdall 

 Reid had his fling in attempting to mystify your 

 readers with a facetious misrepresentation of the 

 proper use of the term "acquired characters." The 

 fictitious nature of the case presented by him was 

 exposed at that time, and he adds nothing to it to-day. 

 It would be sufficient to refer your readers to that cor- 

 respondence, the mention of which is avoided by Sir 

 Archdall Reid on the present occasion, were it not 

 difficult for many people to obtain the volumes in 

 which it occurs. 



I may, therefore, state here that Sir Archdall Reid's 

 joke or trick consists in ignoring the special and 

 definite significance which has been given (originally, 

 I believe, by Wallace) to the term "acquired charac- 

 ters," namely, that of an English equivalent or code- 

 term for Lamarck's words "les changements acquis." 

 He, on the present occasion, as in 191 1, deliberately 

 and professedly treats the statements of accredited 

 writers concerning " acquired characters " as though 

 they were using those two words in what he calls 

 their "natural sense," and not (as they themselves 

 declare they are using them) in the special Lamarrkian 

 sense as a "code-term." He thus creates confusion 

 and mystification. He declares that every character 

 which makes its appearance in the course of develop- 

 ment from the egg-cell to the end of life is in the 

 natural sense of those words an " acquired character," 

 and he charges writers who maintain that " acquired 

 characters " are not transmissible with making a 

 statement which is " purely nonsensical." " There is," 

 says Sir Archdall Reid, " absolutely no meaning in the 

 Neo-Darwinian statement that acquired characters are 

 not transmissible. It is like a declaration that five 

 miles weigh five pounds." To that the obvious reply 

 is : " If you, without any warrant, alter the estab- 

 lished 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." 



Though many readers of Nature are undoubtedly 

 acquainted with Lamarck's " Philosophie Zoologique " 

 and the careful definition given by him of what he 

 meant by his words "les changements acquis," it is 

 desirable to cite here what Lamarck said, since Sir 

 .Archdall Reid, in order to give an air of sincerity to 

 his little joke, poses as an ignoramus, and possibly 

 others really do not bear in mind Lamarck's state- 

 ments. Sir -Archdall Reid says (November 25) : " I 

 daresay I am wrong, but I should be glad to learn 

 just how I am wrong." Further, he writes : " If it 

 be thought that I am mistaken as to all this, can 

 anyone tell us in precise terms what in the world the 



NO. 2668, VOL. 106] 



Lamarckian controversy was about?" It is difficult 

 to suppose that Sir Archdall Reid has not read his 

 Lamarck, and still more difficult to believe that he 

 has forgotten the letters published in Nature in 191 1 

 and 1912, where he was plainly told "just how he is 

 wrong," and also what the Lamarckian controversy 

 was, and is, about. In any case, 1 will now quote 

 what Lamarck wrote about " les changements acquis " 

 and state what the Lamarckian controversy was, and 

 is, about. Lamarck enunciated in his " j'hilosophie 

 Zoologique" (Martin's edition, vol. i., p. 235) two 

 laws, the first of which postulates the production of 

 departures in shape and structure of the organs of an 

 animal from the shape and structure normal to the 

 species in normal conditions — when the animal is sub- 

 jected to what were hitherto unusual conditions ; * 

 whilst the second asserts that the changes thus 

 acquired ("acquired characters" of English writers) 

 are transmitted in generation to offspring. The 

 limitations given by Lamarck's own words must, of 

 course, be carefully observed. Lamarck writes : 



"Premiere Loi. — Dans tout animal qui n'a point 

 d^pass^ le terme de ses d^veloppements, I'emploi 

 plus frequent et soutenu d'un organe quelconquc 

 fortifie peu k peu cet organe, le d^veloppe, I'agrandit 

 et lui donne une puissance proportionnee a la duree 

 de cet emploi; tandis que le d^faut constant d 'usage 

 de tel organe I'alfaiblit insensiblement, le detcjriore, 

 diminue progressivement ses facult6s, et finit par le 

 faire disparaitre. * 



" Deuxi^me Loi. — Tout ce que la nature a fait 

 acqu^rir ou perdre aux individus par I'influence des 

 circonstances ou leur race se trouve depuis longtemps 

 e.\pos6e et, par consequent, par I'emploi predominant 

 de tel organe, ou par celle d'un defaut constant 

 d 'usage de telle partie ; elle le conserve par la 

 generation aux nouveaux individus qui en proviennent, 

 pourvu que les changements acquis soient coni- 

 muns aux deux sexes, ou k ceu.x qui ont produit tcs 

 nouveaux individus." 



Those are Lamarck's two laws. The first is uni- 

 versally admitted to be a correct statement of observed 

 fact in numerous cases, though it is not to be 

 accepted as formulating a primary or fundamental 

 property of living matter. 



The second law — stating that "les changements 

 acquis " (for which words, in the exact sense in which 

 Lamarck used them, the English term "acquired 

 characters " was many years ago adopted and estab- 

 lished as an equivalent) are preserved by generation to 

 the new individuals born from the parents which have 

 acquired those changes in accordance with the first 

 law — has been challenged by many naturalists and 

 accepted by others. Lamarck makes it abundantly 

 clear that the characters transmitted to a new genera- 

 tion — with which he is concerned — are changes in 

 form and structure acquired by the parents as a result 

 of more frequent and sustained use of some organ or 

 of constant disuse of such organ resulting from the 

 influence of circumstances to which their race has 

 been for a long time exposed. It would have ren- 

 dered misapprehension more difficult had the term 

 "acquired changes" been adopted instead of "acquired 

 chardcters " as the English equivalent of " change- 

 ments acquis." The distinctive attribute of the 

 acquired characters so indicated and defined is that 

 they are departures (either increase or decrease) from 

 the usual or normal size, form, or structure of this 

 or that part, arising in an organism " which has not 

 yet passed the limit of its [individual] development" 

 when that organism is submitted to novel conditions. 

 They are novelties which arise under novel conditions, 

 departures from the normal which occur when the 

 environment ceases to be — in certain important par- 



