598 ROBERT H. BOWEN 



in a general way with those of Meves. The chromosome 

 numbers in the large and small generations seem not to ha^e 

 been examined carefully, but if they are the same, as seems 

 probable, the Lepidoptera might be considered as another 

 example of the ' polymegaly ' which Montgomery (1910) 

 first described fully in Hemiptera. 



I have recently (Bo wen, 1922 c) given a full account of this 

 particular type of spermatic polymorphism in the family 

 Pentatomidae (Hemiptera), to which reference may be 

 made for the details of this phenomenon. It may be pointed 

 out, however, that in one important respect the conditions in 

 the Hemiptera and Ijepidoptera differ markedly ; for while in 

 the former all the cells, regardless of size, give rise to normally 

 formed sperms, in the latter the small generation seems to 

 give rise only to abnormal sperms, although the small spermatids 

 may first proceed for some time on an apparently normal 

 course, as noted above. Furthermore, in the Hemiptera all the 

 spermatocytes and spermatids in a given testicular lobe are 

 involved, while in the Lepidoptera only part of the cysts in 

 each lobe are affected and these apparently without any notice- 

 able plan. It may also be noted that in the Lepidoptera the 

 appearance of the polymorphic cells seems to be an accompani- 

 ment of testicular old age, while such a relation is entirely 

 lacking in the Hemiptera. 



Notes on the Spermatocytes and the Spermatocyte 



Divisions. 



The notes in this section deal only with Callosamia. 



In Callosamia the mitochondria are present in spermato- 

 cytes of the growth period in the form of very numerous 

 vesicular spheres or o voids (fig. 42), approaching most nearly 

 in general appearance those figured by Gatenby (1917 «) in 

 Smerinthus populi and Pier is brassicae. They 

 tend to be accumulated particularly in one region of the 

 cytoplasm, and in my preparations are usually so closely packed 

 that they give the impression of a mass of soap bubbles. I wish 



