372 :\IODKRX THKORIliS OF HEREDITY. 



theory in his books, and it may be assumed that, while he may 

 not have doubted the possibility of acquired characters being 

 inherited, he did not regard this as of much importance in 

 comparison with the inheritance of small continuous fluctuations.* 

 In stating, as has frequently been done in the last few years, 

 that Darwin's views are discredited by the leading students of 

 heredity to-day. we must distinguish carefully the two assump- 

 tions involved in his theory: ii) That small continuous varia- 

 tions are inherited; (2) that natural selection causes survival of 

 the fit and elimination of the unfit. I venture to doubt whether 

 any sane scientist has ever disputed the second of these doctrines, 

 but, as Lock in his recent book on Heredity admirably expresses 

 it : " It does not follow that natural selection, directing the 

 accuinulatioii of minute differences, has been the method by 

 which adapted forms have originated." Lock illustrated this 

 remark by a reference to the well-known capacity of lizards to 

 regenerate their tails if deprived of them by any accident. The 

 power of regenerating tails may clearly be of service to the 

 organism, but if the evolution of such a power is to be explained 

 on Darwin's theory, we have to admit two remarkable supposi- 

 tions : ( I ) That a partly regenerated tail, in every stage of the 

 process, is useful to a lizard; and (2) that such competition 

 exists between lizards which have lost their tails that those which 

 could regenerate them would survive rather than the others. 

 The first supposition is conceivable, though highly improbable, 

 but the second is absurd, since, by the same argument, how much 

 more would all injured lizards be exterminated in competition 

 wuth uninjured ones! 



Since Darwin's time the theory which has had the greatest 

 influence on modern thought, in connection with the problems of 

 heredity, is that brought forward nearly twenty years ago by 

 Weismann. 



Before stating the essential point of this theory, it is neces- 

 sary to recall certain well-known facts in connection with the 

 reproduction of animals and plants. In the ordinary process of 



* In Darwin's " Life and Letters." however, he makes some very 

 disparjiging remarks about Lamarck's views ; T have noted the following 

 amongst others : " Lamarck nonsense ". ... a few sentences later saying 

 that he (Darwin) had come to "conclusions not widely different from his. 

 though the means of change are wholly so" (loc.cit., ii, 23); "veritable 

 rubbish" (loc. cit.. ii, 29); "absurd though clever work" (luc. cit.. ii. 

 39L 



Since this paper was written I have read Dr. Traill's paper on 

 "Atmospheric variation as a factor in organic evolution" (see Report S.A. 

 Association for Advancement of Science, Cape Town, tqio, pp. 290-305). 

 While T must confess to a total inability to consider Dr. Traill's views 

 seriously. I should like to point out that, in arguing against the possibility 

 of the inheritance of acquired characters, he speaks of the latter as one 

 of the essential points of " Darwinism." This is, as we have seen, not 

 the case, though the mistake is a rather common one. Since Dr. Traill 

 has been careful to leave the carrying out of any observation or experi- 

 ment in support of his main theory to others, it is hardiv worth while 

 to waste any time in discussing the latter. 



