NOVBMBEE 20, 1896.] 



SCIENCE. 



737 



in the life- struggle, and it matters not 

 whether the adaptation as reached through 

 individual modification of the bodily tissues, 

 or through racial variation of germinal ori- 

 gin. So long as the adaptation is there— 

 no matter how it originated— that is sufl&- 

 cient to secure survival. Prof. Weismann 

 applies tliis conception to one of those 

 difficulties which have been urged by critics 

 of natural selection. '^ Let us take," he 

 says,* '' the well-known instance of the 

 gradual increase in development of the deers' 

 antlers, in consequence of which the head, 

 in the course of generations, has become more 

 and more heavily loaded. The question 

 has been asked as to how it is possible for 

 the parts of the body which have to support 

 and move this weight to vary simultaneously 

 and harmoniously if there is no such thing 

 as the transmission of the effects of use or 

 disuse, and if the changes have resulted 

 from processes of selection only. This is 

 the question put by Herbert Spencer as to 

 ' co-adaptation,^ and the answer is to be found 

 in connection with the process of intra- se- 

 lection. It is by no means necessary that 

 all the parts concerned — skull, muscles and 

 ligaments of the neck, cervical vertebrae, 

 bones of the fore-limbs, etc — should simul- 

 taneousl}'' adapt themselves hy variation of the 

 germ to the increase of the size of the ant- 

 lers, for in each separate individual the 

 necessary adaptation will be temporarily 

 accomplished by intra- selection,'' that is, by 

 individual modification due to the innate 

 plasticity of the parts concerned. '' The im- 

 provement of the parts in question," Prof. 

 Weismann urges, " when so acquired, will 

 certainly not be transmitted, but yet 

 the primary variation is not lost. Thus 

 when an advantageous increase in the size 

 of the antlers has taken place, it does not 

 lead to the destruction of the animal in con- 

 sequence of other parts being unable to suit 

 themselves to it. All parts of the organism 

 * Komanes Lecture, pp. 18, 19. 



are in a certain degree variable \i. e., modifi- 

 able] and capable of being determined by the 

 strength and nature of the influences that 

 affect them ; and this capacity to respond 

 conformably to functional stimulus must be 

 regarded as the means which make possible 

 the maintenance of a harmonious co-adapt- 

 ation of parts in the course of the phyletic 

 metamorphosis of a species. * * * As the 

 primary variations in the phyletic meta- 

 morphosis occurred little by little, the sec- 

 ondary adaptations would as a rule be able 

 to keep pace with them." 



So far Prof. Weismann. According to his 

 conception, variations of germinal origin 

 occur from time to time. By its innate 

 plasticity the several parts of an organism 

 implicated by their association with the 

 varying part are modified in individual 

 life in such away that their modifications 

 cooperate with the germinal variation in 

 producing an adaption of double origin, 

 partly congenital, partly acquired. The or- 

 ganism then waits, so to speak, for a 

 further congenital variation, when a like 

 process of adaptation again occurs ; and 

 thus race-progress is effected by a series of 

 successive variational steps, assisted by a 

 series of cooperating individual modifica- 

 tions. 



If now it would be shown that, although 

 on selectionist principles there is no trans- 

 mission of modification due to individual 

 plasticity, yet these modifications afford the 

 conditions under which variations of like 

 nature are afforded an opportunity of oc- 

 curing and of making themselves felt in 

 race-progress, a further step would be taken 

 towards a reconciliation of opposing views. 

 Such it appears to me, may well be the 

 case. 



To explain the connection which may 

 exist between modifications of the bodily 

 tissues due to innate plasticity (intra-se- 

 lection) and variations of germinal origin 

 in similar adaptive directions, we may re- 



