STUDIES ON INSECT SPERMATOGENESIS. 



403 



cells, but specific ones which can be identified by reason of various 

 individual peculiarities can be readily recognized in both large and 

 small generations. Similarly, the metaphase plates are roughly alike 

 in area, though the chromosomes may be sometimes slightly more 

 spread out than at others. Such is the case in Text-figure 4A; but 

 other plates of the same kind are often more compact. The point of 

 importance is that the plates are of approximately equal extent 

 (absolute, not relative), so that regardless of the amount of cytoplasm 

 and the length of the spindle the chromosomes in the large spermato- 

 cytes form a metaphase plate essentially like the one they would have 

 formed in a cell of very much smaller volume (compare Text-figs. 

 4 A and B). On the other hand, the spindle lengths (measured from 

 centriole to centriole at metaphase) are approximately proportional 

 to the size of the cells. I have made a long series of measurements 

 (with a filar micrometer) of the spindles in Arvelius, with the results 

 shown in Table II. Examples from the large cells were scanty, but 

 sufficient to establish the general proposition beyond question. Fin- 

 ally, and perhaps of most interest, the sizes of corresponding chromo- 

 somes seem to he the same in all cells regardless of their size. It was upon 

 this point that Montgomery placed special emphasis. I have tried 

 to check his results critically in Arvelius, which is a much more favor- 

 able form than Euschistvs for this purpose. My results failed of a, 

 rigorous demonstration of chromosome equality, in part because of 

 inadequate material but chiefly because of the lack of any sufficiently 

 precise method of measurement. Nevertheless, disregarding the 

 slight and accidental differences which are bound to appear in such 

 direct comparisons as those of Text-figures 4:A and B, it appears that 

 the corresponding chromosomes are of sizes which, if not exactly 

 identical, certainly correspond within very small limits of difference. 



TABLE II. 



Ratio of spindle lengths. The average length of the spindle in a cell from 

 the "normal" generation is taken as unity (1.0). 



The enormous increase in the amount of cytoplasm in dimegaly has 

 already been noted and it remains now to examine the behavior of its 

 various formed elements. It might naturally be supposed that in a 



