No. 4-] MALE REPRODUCTIVE CELLS OE INSECTS. 193 



232 and 236)! I regard this body as the centrosome which is 

 left in each spermatid after the last spermatocyte division, and 

 I also believe it to be identical with the very conspicuous body 

 which forms the neck of the spermatozoon (PI. V, Figs. 196- 

 200). The chromatic substance fuses into a smoothly contoured 

 mass, which soon assumes a crescent shape so common in insect 

 spermatogenesis. The neck-body lies within the nuclear mem- 

 brane opposite the concavity of the chromatic crescent (Figs. 

 198-200). The chromatin undergoes chemical and physical 

 changes during the metamorphosis of the spermatid, but the 

 neck-body remains practically the same in size, and does not 

 alter its affinity for stains. It becomes the neck of the sper- 

 matozoon (PI. IV, Figs. 139-158; PI. V, Figs. 196-200). The 

 chromatic crescent is at first less dense and stains less deeply ; 

 then it becomes concentrated, and stains nearly black by 

 Heidenhain's method. These changes in density are not well 

 shown in the figures. At the same time it becomes elongated, 

 one end applying itself to the neck-body, the other becoming 

 the tip of the spermatozoon head." 



Although the writer has not yet had the opportunity to 

 examine the cells of Caloptenns, he cannot but regard the views 

 of Wilcox as erroneous. The close correspondence between the 

 body which Wilcox designates, doubtfully, a nucleolus in one 

 place and a centrosome in another, and the structure which has, 

 in XipJiidhmi, been traced through the various developmental 

 stages of the spermatozoon as an accessory chromosome, in- 

 dicates that the phenomena of development are quite similar 

 in the two cases. The centrosomes in XipJiidiiivi, so far as 

 observed, are quite small, and could in no case be mistaken for 

 such objects as Wilcox represents in the cells of Caloptenns. 



The absence of literature has prevented any further compara- 

 tive study of the subject, unfortunately, but reference must be 

 made to the figures of Henking ^ upon the spermatogenesis of 

 PyrrocJioris, in which there seems to be something similar to the 

 appearances found in XipJiidiii7n. Figs. 16 and 17 show a body 

 marked "n" that, so far as represented, might correspond to 



^ Henking ('91), " Erste Entvvickelungsvorgange in den Eiern der Insecten," 

 Zeit.f. wiss. Zool., Bd. li, p. 685. 



