271 



Nachdruck verboten. 



Amitosis as a Factor in normal and regulatory Grrowth. 



By C. M. Child. 

 With 12 Figures. 



The added knowledge of cell phenoraeua gained during the last 

 ten years has led many cytologists to believe that the views so strongly 

 urged by Ziegler and Vom Rath regarding the significance of amitosis 

 are too extreme. Various observations and experiments have been re- 

 corded which seem to demonstrate that mitosis may follow amitosis 

 and that amitosis may occur »rmally in cells which are far from 

 death and degeneration. Nevertheless this form of nuclear division 

 has been regarded as of secondary importance and has received com- 

 paratively little attention in the development of cytological knowledge 

 and theory. For example Wilson in his work on the cell ('00) ex- 

 presses himself regarding it as follows: "It is of extreme rarity, if 

 indeed it ever occurs in embryonic cells or such as are in the course 

 of rapid and continued multiplication" (p. 118); and again after a 

 resum6 of the literature and the views expressed by different authors 

 with special reference to the work of Meves ('94), Preusse ('95) and 

 Pfeffer ('99): "This seems to show conclusively that amitosis, in 

 lower forms of life at least, does not necessarily mean the approach 

 of degeneration, but is a result of special conditions. Nevertheless 

 there can be no doubt that Flemming's hypothesis in a general way 

 represents the truth and that in the vast majority of cases amitosis is 

 a secondary process which does not fall in the generative series of 

 cell divisions" (p. 119). But on page 285 he refers again to Meves' 

 observations on the spermatogonia of the salamander as "strong evi- 

 dence" that mitosis and normal development of spermatozoa may follow 

 amitosis in the salamander. 



GuRV^iTSCH ('04) says in his review of the subject : "Die Ansichten 

 auf diesem Gebiet haben gerade in den letzten Jahren wichtige Um- 

 wandlungen erfahren, indem man jetzt ziemlich allgemein geneigt ist, 

 der Amitose eine größere biologische Wertigkeit beizumessen, als es 

 ihr seitens der älteren Autoren, namentlich Flemming und besonders 



