34^ Appe7idix A 



is a factor in survival which cooperates with adaptation through 

 germinal variation. 



5. Weismann, following the lead of Roux, interpreted indi- 

 vidual modification in terms of intra-selection. He clearly saw 

 the implication given in 4 above. Speaking of ' the well-known 

 instance of the gradual increase in the development of deer's 

 antlers,' he says {Ro7nanes Lecture, 1894, p. 18): 'It is by no 

 means necessary that all the parts concerned should simultane- 

 ously adapt themselves by variation of the germ to the increase 

 in size of the antlers ; for in each separate individual the neces- 

 sary adaptation [accommodation] will be temporarily accom- 

 plished by intra-selection — by the struggle of parts — under the 

 trophic influence of functional stimulus.' 



6. So far there is no direct relation between specific modifica- 

 tions and specific variations. Individual accommodation, as a 

 factor in survival, affords time (Weismann, op. cit., p. 19) for the 

 occurrence of any variations of an adaptive nature. 



7. My own modest contribution to the further elucidation of 

 the subject is the suggestion (i) that where adaptive variation v 

 is similar in direction to individual modification ;;z, the organism 

 has an added chance of survival from the coincidence m -{- v \ 

 (2) that where the variation is antagonistic in direction to the 

 modification, there is a diminished chance of survival from the 

 opposition m — v\ and hence (3) that coincident variations will 

 be fostered while opposing variations will be eliminated. 



8. If this be so, many of the facts adduced by Lamarckians 

 may be interpreted in terms of the survival and gradual estab- 

 Hshment of coincident variations by natural selection under the 

 favourable environing conditions of somatic modifications. 



9. It is clear that there is nothing in this suggestion of a 

 direct relation between specific accommodation and coincident 

 variation which can be antagonistic to the indirect relation 

 indicated above in 6. 



ID. Correlated and coexistent variations would have the same 

 relations to coincident variations as obtain in other cases of 

 natural selection.^ 



1 Nos. 6, 9, 10 bear upon Chapter XIV. above. — J. M. B. 



