'STUDIES OF AMITOSIS 503 



ing the pre-cannibal, the cannibal, and the post-cannibal periods, 

 a little over 13 per cent are mitotic and a little less that 87 per cent 

 amitotic. He concludes from this that amitosis plays in this 

 case ''an important, if not the chief, part in the differentiation 

 of a definitive tissue." (P. 246.) 



Pacaut ('09, as cited by Des Cilleuls, '14), in his work on the 

 epithelial cells of mammalian cornea, proposed a hypothesis 

 that amitosis is due to the insufficient elimination of poisonous 

 deposits accumulated in the cells during their metabolic activity. 



Wieman ('10) claims that amitosis in germ cells is followed by 

 mitosis in the ovaries and testes and nurse cells of Leptinotarsa. 

 He believes that amitosis is due to a fluctuation in the nutritive 

 supply of the cells brought about by a 'stimulus to a rapid cell 

 division which causes a temporary derangement in the normal 

 metabolism, and so amitosis and mitosis stand, as he conceives, 

 for the extremes of a continued series, but representing different 

 types of metabolism. 



Foot and Strobell ('11) described in the ovaries of Protenor, 

 the amitotic division of certain cells which later produce ova. 



Payne ('12) shows that in Gelastocoris, the cells which appar- 

 ently multiply by amitosis do not produce ova. 



Jordon ('13 a), working on the amitotic division of ciliated 

 cells in the epididymis of some vertebrates, considered the ab- 

 sence of the centrosome to be the fundamental cause of this 

 kind of division; it having been. known that the centrosome is 

 destroyed in the formation of the cilia in such cells. 



Des Cilleuls ('14), after reviewing all the more important 

 papers on the subject, and apparently being supp'orted in his 

 own observations on epithelial cells of the vitrine cornea of the 

 rabbit, asserts that amitosis is a process of the generative nature 

 of a cell and not the sign of its senescence. 



Hegner ('14) concludes, from all the evidences available, that 

 amitosis has not been demonstrated in the germ cells. He 

 could not demonstrate with certainty amitotic division among 

 the oogonia or spermatogonia of chrj^somelid beetles, even in 

 the slides sent to him by Wieman. 



Arber ('14), in her work on the development of the adventi- 



