50 KANSAS UNIVERSITY SCIENCE BULLETIN. 



(Fig. 16.) As the cell begins to elongate, the nucleus goes to 

 one end, namely, that toward the periphery of the cyst. (Figs. 

 14 and 15.) The chromatin again frequently appears in patches 

 as the cell decreases in size. (Figs. 33 and 36.) In many cells 

 the patches never disappear. When it has diminished to less 

 than half its maximum diameter, the nucleus begins to elon- 

 gate, becoming elliptical, and finally forms the long, tube-like 

 head of the spermatozoon. (Figs. 43 and 45.) 



I found here that the nucleus was hollow, or, better, that it 

 showed a clear space within. For a long time it contains the 

 many chromatin granules, as seen in figs. 39, 40, and 41 ; but 

 at last the walls seem to attract all these granular masses, and 

 the center is entirely clear, as in fig. 45. In fig. 44 are shown 

 cross-sections of spermatozoa heads, of the stage of fig. 43. In 

 fig. 45 we have a mature spermatozoon head. 



The accessory chromosome in Gryllus lags behind during the 

 spermatogonial divisions, just as in Xiphidium (McClung, '99), 

 and retains its identity all through the growth period, in many 

 cases becoming quite large. At first it cannot be distinguished 

 in the spermatid, but soon its stronger stain and exemption 

 from disintegration make it apparent. (Fig. 4.) It is flattened 

 against the nuclear wall and, unlike Paulmier's ''small chro- 

 mosome," it does not break up but remains intact, as Henking 

 and McClung have described. (Figs. 14, 18, 32, 37, and 

 others.) It gets larger and then smaller, and is finally lost in 

 the rest of the chromatin, as the latter condenses to form the 

 spermatozoon head. I was not able to see that it occupied one 

 side of the elongating head, as McClung describes it in Xiphi- 

 dium. The darker stain and regular contour, and sometimes 

 its greater size, made it in most stages quite evident. 



(6) CYTOPLASMIC STRUCTURES. 



It is in the cytoplasmic structures that Gryllus shows some 

 things that have not been described, so far as I know ; yet I 

 almost hesitate to enter the discussion concerning the nebenkern, 

 the mitosome, the idiozome, the archoplasm, the attraction 

 sphere, the acrosome, the "mitochondrion korper" and other 

 bodies which have been described in the extra-nuclear parts of 

 the germ-cell. But because I have been unable to find in any 

 of the papers a description of a structure like the one in Gryllus, 

 I shall proceed to describe the nebenkern as I find it. I shall 



