252 Kansas Academy of Science. 



of the sex chromosomes. Both may be essential factors in this 

 connection, in varying degrees of relative importance. 



In spite of the highly critical attitude maintained toward 

 the question of modification of the germ cells through in- 

 fluences from the environment, so much good evidence is ac- 

 cumulating that we cannot ignore these cases nor cry them out 

 of court. While we can readily see how external influences 

 acting upon the germ cells may so modify them that the off- 

 spring will be in some way influenced, it is difficult to accept, 

 without more convincing proof, the experiments designed to 

 demonstrate that characters acquired by the soma are trans- 

 mitted to the germ cells in such fashion as to produce similar 

 modifications in the soma of the offspring. 



The experiments of Brown-Sequard, Kammerer and others, 

 by which it is claimed that modifications such as injuries, 

 changed instincts, changed color patterns, etc., are trans- 

 mitted to future generations, have been so interpreted. It 

 is so difficult to conceive of the mechanism by which these 

 changes in the soma could be transmitted to the germ cells 

 that we should demand far better proof than has thus far 

 been brought forward; yet above all things, while we should 

 maintain an attitude of skepticism, we should be free from 

 dogmatic intolerance toward any really creditable work along 

 these lines. 



Much needs to be done in tracing out the effect of the en- 

 vironment upon fecundity and periodicity in reproduction. To 

 what extent are these results attributable to modification of the 

 germ cells? To what extent may these changes be inherited? 

 While we have some data upon these points, as, for instance, in 

 the case of sheep, the field is large and much needs to be done 

 in it. 



Domestication of animals introduces a whole series of com- 

 plex factors involving change of food, modifications of climate, 

 protection from the weather, modification or loss of instincts, 

 etc. These all exert a profound influence upon the reproduc- 

 tion of animals. It would be difficult in most cases to say in 

 how far selection might also play a part. We know that in 

 many failures to breed wild animals it plays no part. Little 

 has been done since the time of Darwin upon these important 

 subjects. Our attention has been so closely fixed upon the 

 study of the mechanism of reproduction that we have largely 



