RELATION BETWEEN AMITOSIS AND MITOSIS. I 73 



Doubtless various other conditions may arise in the cell which 

 favor amitosis, but the above consideration is sufficient to indi- 

 cate the relation between the facts and the hypothesis. 



The opinion of Ziegler and Vom Rath (Ziegler, '91 ; Ziegler, 

 and Vom Rath, '91 ; Vom Rath, '95) and many later observers, 

 that amitosis is never followed by mitosis, but always leads to 

 degeneration and death is without doubt incorrect. But that 

 degeneration and death should follow amitosis in certain cases is 

 to be expected, if my hypothesis is correct. Under extreme con- 

 ditions the nucleus or cell many be forced so far from equilibrium 

 that changes occur which render return impossible, and degen- 

 eration and death follow. In regions of rapid embryonic growth 

 degenerating nuclei are not infrequently found, but in these, as in 

 other cases, the degeneration is not a necessary consequence of 

 the amitosis, but both are merely indications of a physiological 

 condition, which in many cases brings about amitosis without de- 

 generation, but in extreme cases produces degeneration. Nuclear 

 fragmentation is a frequent accompaniment of degeneration, but 

 even in these cases the physiological conditions may be in general 

 similar to those occurring in normal amitosis. 



Returning now to the case of Moniezia, the facts concerning 

 the distribution of relative frequency of amitosis and mitosis are 

 briefly as follows. As regards the germ cells, amitosis is much 

 more frequent than mitosis during the development of ovaries and 

 testes (Child, '07a, '07&). Mitoses are of very rare occurrence 

 during the earlier stages of development, but in some chains and 

 proglottids and gonads appear somewhat more frequently in later 

 stages before the growth-period. This developmental period 

 characterized by amitosis is followed by the growth-period, at the 

 beginning of which a spireme appears, and later by maturation. 

 In the female cells maturation exhibits the features typical of the 

 process in other species (Child, 'oya) : in the male cells typical 

 maturation occurs, but in addition to this a peculiar process of 

 fragmentation of the nuclei of the first spermatocytes is of com- 

 mon occurrence (Child, '07$), and apparently results in the for- 

 mation of nuclei indistinguishable from the spermatid-nuclei 

 formed in the typical manner. Whether these nuclei actually 

 give rise to spermatozoa or not cannot be determined with cer- 



