412 E. L. SHAFFER. 



movements during metakinesis which Conklin has shown, plays 

 such an important role in the localization of cytoplasmic sub- 

 stances in the egg. 



There is no evidence from my observations on Passalus that 

 the mitochondria divide autonomously, as has been maintained 

 by some workers. As the cell constriction continues through 

 the equator of the spindle (Figs. 14, 35), the mitochondria are 

 divided by this constriction and the daughter cells (second 

 spermatocytes) receive approximately equal amounts of mito- 

 chondria. The mitochondrial masses then move a short distance 

 toward the poles; this is evidently caused by a further elonga- 

 tion of the spindle. Montgomery (1911) has described a similar 

 method of division in Euschistus. The fact that mitochondria 

 are found in equal amounts in daughter cells is supposed by some 

 to favor the view that they divide autonomously; but it is 

 well known that yolk and similar substances are often found in 

 equal amounts in daughter cells, yet no one maintains that yolk 

 granules divide autonomously. Faure-Fremiet (1911) describes 

 autonomous division in the mitochondria of the Protozoa, and 

 Wilke (1912) does likewise for the spermatocytes of Hydrometra. 

 Payne (1917) does not incline strongly to the view that the 

 mitochondria are divided by the cell constriction, while Lewis 

 and Robertson (1916) do not clearly state whether their division 

 in Chorthippus is autonomous or passive. 



Following the first maturation division, there is a short inter- 

 kinesis during which the second maturation spindle is formed 

 (Figs. 1 6, 36). At this time the mitochondria are lying at one 

 side in a rather dense mass which shows a lighter central portion 

 through which the spindle of the previous division passed. The 

 behavior of the mitochondria during the second maturation 

 division is precisely the same as in the first division (Figs. 17, 37). 

 They again surround the spindle peripherally and are divided 

 by the equatorial constriction. As a result of this division both 

 spermatids receive approximately equal amounts of mitochondria 

 (Fig. 1 8). 



The mitochondrial mass contained in the spermatid gradually 

 becomes more compact and henceforth may be designated as 

 the Nebenkern. It stains intensely with the basic stains and 



