INSECT SPERMATOGENESIS 615 



the Golgi bodies. These spherical vesicles are then deposited 

 on the nuclear wall, and gradually fuse to form the acrosome, 

 the granules differentiated within them fusing at the same time 

 to form a single large acrosomal granule. As the acrosomal 

 vesicles are deposited the Golgi bodies are cast off. as in the 

 formation of the acrosome in other animals, and move off down 

 the tail. It is clear in my Pygaera preparations that the 

 formation of the vesicles by the Golgi bodies is not completed 

 simultaneously in all of them, but rather that there is a gradual 

 production and deposition of the vesicles extending over a con- 

 siderable period, and concluded only at a relatively late stage 

 (figs. 13, 15, 16). Figs. 1 and 2 show the latter part of the 

 acrosomal formation in progress. The acrosomal granule in 

 Pygaera stains very intensely and is of extraordinary size, 

 often concealing the vesicular portion, especially if the latter 

 is not well differentiated by the staining. Several Golgi bodies 

 are grouped around the acrosome, and particularly in fig. 2 

 one gets the impression that one or two of them are in the act 

 of depositing the small acrosomal vesicle which each has 

 elaborated. Not infrequently the acrosome is multiple, as 

 in fig. 2, one portion being much the smaller, but later on these 

 parts always merge into a single acrosome. Gatenby shows this 

 process in his Text-fig. 4, and with the general plan of this 

 figure I am in entire agreement. The Golgi bodies seem to 

 clear away from the acrosome as they deposit their quotas, 

 and thus they tend to be scattered along the tail rather than 

 to be collected in a single group. In the later stages of deposi- 

 tion the acrosome in Pygaera can be very clearly separated 

 into its two fundamental constituents — the intensely-stained 

 acrosomal granule and the clear, unstained acrosomal 

 vesicle (figs. 13 and 15).-'^ The contour of the vesicular 

 portion is at first rather irregular, which I take to be indicative 

 of its multiple origin ; but the irregularities are gradually 



1 I have found the material of the acrosomal vesicle very difficult to 

 differentiate sharply in the earlier stages. It is, furthermore, often obscured 

 by the enormous acrosomal granule, so that in my figures of young sper- 

 matids the vesicular part of the acrosome may not appear at all. 



