The Histogenesis of Cysticercus pisiformis. 243 



to my "nuclear granules". He says further ■'. . , often two or three 

 of these small bodies are seen, sometimes appearing as if in contact 

 with the nuclear membrane along the line of the constriction 

 (figs. 5b and 11a)." The appearance presented in fig. 5b is similar 

 to that in my Fig. 5. I consider the "small bodies ... in contact 

 with the nuclear membrane" as probably sharing in the formation 

 of the latter. And further "Whether the new nucleolus arises in 

 all cases from the old I have been unable to determine with cer- 

 tainty ... I think it not impossible that the new nucleolus may, 

 in some cases at least, arise independently of the old." I have de- 

 termined with a high degree of probability that it does arise in- 

 dependently of the old in my preparations. Under "General Con- 

 siderations" (p. 556), he says : "It is scarcely possible that Moniesia 

 difters from the majority of other forms in tlie amitotic multipli- 

 cation of its sexual nuclei." This statement is open to grave doubt. 

 While I have not studied the development of the sexual organs in 

 Taenia serrata, Child's account shows that mitoses are exceedingly 

 rare in the development of these organs in Moniezia}] In the sper- 

 matogenesis and ovogenesis of other animals, on the contrary, one 

 finds not only numerous mitoses, but the structure of the resting 

 nuclei show the chromatin arranged in a network instead of in 

 "nucleoli" as described by Child. Eegarding the individuality of 

 the chromosomes and the germ plasm, he says (p. 557): "If cells 

 which pass thru a long history of amitotic division are capable of 

 giving rise to sexual cells, it is difficult to see how the hypothesis 

 of the individuality of the chromosomes can be maintained. De- 

 fenders of this hypothesis may claim that all the chromatin sub- 

 stance is concentrated in the nucleolus, that there is in this a de- 

 finite region or 'sphere of influence' corresponding to each chromo- 

 some, and finall}^ that each new nucleolus arises from the old, each 

 receiving an equal part of the regions. All that can be said 

 against a hypothesis of this sort is that there are no facts to 

 support it. It is difficult, to say the least, to conceive how any 

 equal division of nuclear elements such as Weismann's theory 

 demands could occur in the budding of a minute nucleolus from a 

 larger one. Moreover, it is probable that at least in many cases 

 the new nucleolus arises independently of the old. That a chromo- 

 some is temporarily an individual may be readily admitted; that it 



1) See Appendix. 



