STUDIES IN SPERMATOGENESIS 



PART II. 



(Pages 33-74. Plates VIII-XV.) 



a comparative study of the heterochromo- 



somes in certain species of coleoptera, 



hemiptera and lepidoptera, with 



especial reference to 



SEX DETERMINATION. 



BY N. M. STEVENS 



WASHINGTON, D. C. : 



Published by the Carnegie Institution of Washington 



October, 1906 



