studies on Insect Spermatogenesis. 



V. On the Formation of the Sperm in 

 Lepidoptera. 



By 

 Robert H. Bowen. 



(From the Department of Zoology, Columbia University.) 



With Plates 24-26. 



In a paper published several years ago by Gatenby (1917 a) 

 an account of sperm formation in Lepidoptera was given, 

 certain features of which departed rather widely from the results 

 of previous workers on similar material. Particularly interest- 

 ing from my own point of view were the descriptions of the 

 origin of the acrosome and the history of the mitochondria 

 (' macromitosome ' or nebenkern) in the spermatid, these 

 matters having proved especially difficult to elucidate in the 

 Hemiptera upon which I had resumed work early in 1919. As 

 this work progressed, it became increasingly evident that the 

 facts in the Hemiptera (and in other forms which I have 

 studied subsequently) did not agree with certain important 

 features of Gatenby's account, and aroused the suspicion that 

 perhaps the facts in the Lepidoptera might be open to a some- 

 what different interpretation. I decided accordingly to put up 

 some lepidopteran material for purposes of comparison, and 

 during the last three years this has been done whenever 

 opportunity offered. Consideraljle difficulty was encountered, 

 due to the impossibility of accurately determining the age of 

 pupae from their external appearance, and a proper range of 

 preparations was therefore not easy to obtain. Certain stages 

 are in fact still incomplete, but the general features are now 



