STUDIES OF AMITOsis 487 



insects. This seems to indicate that the changes in adipose 

 cells are of essentially similar nature throughout all the groups 

 of holometaboHc insects. 



b. Observations on Pieris. Tracing the series of changes in 

 the structure of adipose cells of common cabbage worms (Pieris 

 rapae L.), I found the descriptions b}^ other authors on other 

 insects hold fairly good in this case. The adipose cells from the 

 first stage larva (fig. 1) are very small, measuring 12 to 17 micra 

 in diameter, and each of them contains a single spherical nucleus 

 about 4 or 5 micra in diameter. The cell-bod}- is rich in cyto- 

 plasm and shows few vacuoles. A few fat droplets (fig. 3) and a 

 very small quantity of ghTogen (fig. 2) can be demonstrated 

 at this stage. Very rarely mitotic figures are also to be detected 

 (fig. 4). 



In the second stage larvae, the adipose cells are almost twice 

 as large in diameter as in the preceding stage (fig. 5). The nuclei 

 not infrequently show peculiar shapes, indicative of different 

 stages in the process of amitosis. A few of the cells are binu- 

 cleate (fig. 6) . From this stage onward, I have not seen a single 

 mitotic figure in the tissue, but various indications of amitosis 

 taking place rather frequently have been observed. The cyto- 

 plasmic area is much enlarged and contains abundant fat drop- 

 lets (fig. 7), and here glycogen is also demonstrated in a pretty 

 large quantity. In preparations with ordinary fixation, vacuoli- 

 zation of the cytoplasmic area is sometimes carried to the ex- 

 treme, and in such case the whole area presents a reticulated 

 appearance (fig. 6). In ver}^ rare cases, the ramified condition 

 of the nuclei occurs (fig. 8). This is perhaps not a smiilar con- 

 dition to that observed by Perez ('02) in old larvae of Formica, 

 because, while it is apparently related to the degenerative phe- 

 nomenon in Perez's case, the nuclei here show no sign of degenera- 

 tive nature, and the ramification is not quite so extensive. Rami- 

 fied nuclei occur also in later stages, but such condition never 

 becomes veiy prevalent. 



Late in the third stage, some of the cells begin to show pecu- 

 liar spherical granules in the cell-body. These are albuminous 

 granules. In this and in following stages the cells are pretty 



