496 WARO NAKAHARA 



ently not followed by the division of the cell-bod3\ The fact 

 that this phenomenon does not represent a senile condition of 

 the cell may be easily seen, because the cells at these stages are 

 still functionally very young, and it is long afterward that they 

 begin to degenerate. Nuclear division, without following cyto- 

 plasmic division, insures the increase of nuclear surface. The 

 fact that such increase is in close connection with the increasing 

 functional activity of cells is seen in many cases, for example, in 

 silk-gland cells of various insects. At once the idea that amito- 

 sis may be tributary to intense metabolic activity of cells, bring- 

 ing about the increase of nuclear surface, suggests itself, and 

 here we come face to face with one of the most debated ques- 

 tions in cellular biology since the latter part of last century — 

 the significance of amitosis. 



IV. THE SIGNIFICANCE OF .4MIT0SIS 



A. Historical 



Strasburger ('82) and Waldeyer ('88) regarded amitosis in the 

 higher forms as a survival of a primitive process of direct di- 

 vision derived from the Protozoa. Ziegler ('87) noted amitosis 

 in the periblast of fish-eggs and suggested an intimate connection 

 of amitosis and the high specialization of the cell, followed by 

 degeneration. Flemming ('89), working on the amitotic nuclear 

 division in the epithelial cells of the bladder of a salamander, 

 maintains that the process is, at least in this case, a pathological 

 or abnormal one. 



Chun ('90, as cited by Ziegler, '91, Flemming, '91, '92, Wilson, 

 '00, etc.) made a very valuable suggestion that amitosis in the 

 entodermic cells of the radial canal of Siphonophores was for the 

 purpose of ' ' increasing the nuclear surface as an aid to metabolic 

 interchanges between nucleus and cytoplasm." (Wilson, '00, 

 p. 118.) 



Flemming ('91) observed that the true generative multiplica- 

 tion of leucocytes in lymph glands is effected only by means of 

 mitosis, although both mitosis and amitosis occur in wandering 

 cells, and considered those cells undergoing amitosis as being 

 "on the road to ruin." 



