506 WARO NAKAHARA 



and Saguchi ('17) demonstrate the presence of the centrosome 

 in amitotically dividing cihated cells. 



The theory that amitosis is connected with, a degeneration, 

 aberration, or senescence of the cell, is supported by a large 

 number of authorities, amongst whom the names of Ziegler, 

 Flemming, vom Rath, et cetera, may be mentioned. However, 

 as Child ('07a) has well said, it is not strange that degeneration 

 frequently follows amitosis, because the total destruction of the 

 original substance is the necessary consequence of the ortho- 

 dromic process pushed to the extreme, but there is certainly no 

 reason to beheve that such must always be the procedure. We 

 also have no reason for believing that the degeneration of the 

 cell after it has undergone amitosis is due to the latter process. 

 Why cannot this kind of nuclear division be interpreted as in- 

 dicating active metabolic processes in the cell, and the subse- 

 quent degeneration of the cell as being caused by such activities? 

 Indeed, we see that many cases of amitosis cited by various 

 authors can be explained in this way. 



With the present state of our cytological knowledge, amitosis 

 cannot be regarded as any sort of generative process, since the 

 daughter nuclei produced by amitosis are most probably differ- 

 ent in the amount of their chromatin contents. This,, consid- 

 ered in connection with numerous cases of true amitosis, would 

 show that the direct nuclear division is concerned chiefly, if not 

 entirely, with the vegetative function of individual cells, and the 

 possible significance of the phenomenon would be the one sug- 

 gested by Chun ('90) and more recently by Glaser ('05). There 

 are, however, described by certain authors, at least three kinds 

 of data which apparently speak against this theory : 



First: Those presented by Meves ('94), Preusse ('95), and 

 more recently by Wieman ('10), and Foot and Strobell ('11), 

 showing, as it is claimed, that oogonial and spermatogonial cells 

 in certain forms divide by amitosis, but they may subsequently 

 undergo mitotic division and produce normal ova and sperma- 

 tozoa. 



Second: Those supplied chiefly by Child ('04, '07 a, '07 b), ap- 

 parently indicating that amitosis is a normal method of cell- 



