OCCURRENCE OF AMITOSIS IN MONIEZIA. II9 



we must consider it in this way sooner or later, we can find no 

 good reason for regarding it as fundamentally different from many 

 other problems of ontogeny. Physiologically it is no more diffi- 

 cult to conceive that a piece of a nucleus should, under certain 

 conditions, give rise to the characteristic number of chromosomes, 

 than that a piece of the actinian body should give rise to the 

 characteristic number of tentacles. The correctness of the 

 chromosome hypothesis is far from being demonstrated, and in 

 view of this fact we must consider the possibility of revising the 

 hypothesis to fit the facts, as well as that of bringing the facts 

 nto accord with the hypothesis. 



Hull Zoological Laboratory, » 



University of Chicago, 

 December, 1909. 



