STUDIES OF AMITOSIS 495 



h. Mitosis. Berlese ('99-'01) observed that mitotic division 

 takes place in adipose cells during the moulting period in the 

 silk- worm, and he maintained that adipose cells multiply by mi- 

 tosis. According to Deegener ('13), de Sinety ('01) believed that 

 the fat cells may multiply by mitosis without showing any em- 

 bryonal characters. Deegener also cites that Poyarkoff ('10) 

 observed the mitotic division in the case of a beetle larva, Galeru- 

 cella crataegi, just before it enters into moulting period. 



It has already been mentioned that in Pieris the mitotic figure 

 is observable only, and very rarely, in very young larvae. This 

 phenomenon may be interpreted as an indication of embryonic 

 character of the cells, because mitosis does not take place after 

 the cells start their active functioning. Since I found very few 

 mitotic figures, in spite of the large number of adipose cells ex- 

 amined, the occurrence of mitosis in larval adipose cells must be 

 regarded as a very rare phenomenon. Of course, it is not strange 

 that mitosis takes. place when the cells are multiplying, since 

 this is the reproductive method of cells. 



D. General consideration 



Of the nutritive deposits within the adipose cells, the droplets 

 of fat have been known of old. Berlese and Perez discovered 

 another important class of deposits — the albuminous bodies. 

 According to the results of my researches, glycogen is to be con- 

 sidered almost as constant an inclusion as fat, and although not 

 satisfactorily worked out, a mucus-like substance may perhaps 

 be counted as the fourth. 



The deposits of fat and glycogen are found in the cell from an 

 early stage larva, and these substances increase greatly in amount 

 as the stage advances; in later stages the cells store up albumi- 

 nous nutriment. The functional activity of the cells may there- 

 fore be considered to become more and more intense with the 

 advancing ages of the larvae, until histolytic processes set in 

 preparatory to pupation. 



A very interesting fact is that the nucleus of the cell begins 

 to divide by amitosis rather early — long before the albuminous 

 granules start to appear, and that l^he nuclear division is appar- 



