286 C. M. CHILD. 



serrations are essentially identical with my own; he finds it but 

 rarely, in fact he has not figured anywhere a case showing so 

 many mitoses as my Fig. 8 (Child, '070), in which seven cases 

 of mitosis are shown. His argument concerning the ratio of 

 resting to dividing cells in sections (pp. 139-40) concerns matters 

 of which we really know almost nothing one way or the other; 

 moreover, I am fully convinced that in many cases besides 

 Moniezia where the infrequently observed mitoses have been 

 supposed to account for all nuclear increase, numerous amitotic 

 divisions actually occur. But besides all this, my conclusions 

 concerning Moniezia are not based primarily on the frequency 

 or infrequency of mitosis, but upon the actual observation of 

 what I cannot regard as anything but amitosis. The infre- 

 quency or apparent absence of mitosis in many regions of Mo- 

 niezia was what first led me to undertake a further investigation 

 of the material and the remarkable infrequency of mitosis ac- 

 cording to all observers in the neck region, the developing gonads 

 and the genital ducts still seems to me to be highly suggestive, 

 especially when we add to this fact the very frequent occurrence 

 of what seems by all criteria at present available to be direct 

 division. 



Concerning periodicity in mitosis (Richards, 'n, p. 140) 

 the only positive observation which suggests anything of the sort 

 is mine, which was cited in an earlier paper (Child, '10). This 

 was a case of scolex, neck region and a few proglottids in which 

 most of the nuclei were dividing mitotically. I have no means 

 of knowing whether this is a normal occurrence, but if it is, it 

 seems probable that this specimen is a young scolex, for the nuclei 

 throughout the scolex are dividing as well as the others and these 

 nuclei certainly do not take part in the formation of proglottids 

 in later stages. I have considerable evidence for various forms 

 which seems to me to indicate that many organisms or parts 

 may start a period of nuclear multiplication by mitosis, while 

 in later stages amitosis becomes increasingly frequent and it 

 this scolex is normal it may be a case of that kind. It is quite 

 possible, however, that it may be- the result of certain special 

 conditions of which we know nothing and not a normal stage of 

 development in Moniezia at all. 



