No. 524] CHROMOSOMES AND HEREDITY 



461 



makes probable the view that the different chromosomes 

 may have somewhat different functions, and that normal 

 development depends on the normal interactions of the 

 materials produced by the entire constellation of chro- 

 mosomes. 



Boveri himself is far from ascribing to the chromo- 

 somes the intricacies of the Weismannian conception. 

 He has clearly stated that his conception of their individ- 

 uality does not require that each chromosome represents 

 a distinct character of the individual, or even an exclu- 

 sive bundle of such characters. He concedes, that what- 

 ever it is in them that stands for the characters of the 

 adult may be distributed to all of the chromosomes in 

 some species, and that in different species the materials 

 may be differently assorted. 



It should indeed be pointed out that Boveri 's evidence 

 seems to prove too much for that form of the particulate 

 theory that ascribes unit characters to chromosomes, for 

 it indicates, I think, that individual chromosomes do not 

 in any sense contain either preformed germs or determi- 

 nants, or unit characters, or even stand for the produc- 

 tion of particular organs in any sense. 



Were this the case we should expect the isolated blas- 

 tomeres of the dispermic eggs to produce different kinds 

 of organs, heterogeneonsly united. It can not fairly be 

 argued in reply to this point that such development 

 would be a physical impossibility; for, we are familiar 

 with the fact that teeth, hair, bones, etc., may form in 

 various teratomata, and this shows that individual 

 organs may develop independently of the rest of the or- 

 ganism with which they are normally connected. This 

 side of the question has not, I believe, been sufficiently 

 considered by Boveri. 



It is true that Boveri has pointed out that embryos 

 that develop from dispermic eggs are often imperfect or 

 asymmetrical and interprets this as due to the inequali- 

 ties of distribution of the chromosomes. His figures, 

 however, give the impression that the abnormalities are 

 due to imperfections in the relations of the parts rather 



