SPERMATOGENESIS IN PHILOSAMIA CYNTHIA. 



PAULINE H. DEDERER. 



An investigation of spermatogenesis in Philosamia cynthia, a 

 moth of the Saturnid family, was undertaken in the summer of 

 1905, at the suggestion of Professor Crampton, who for some 

 years has been engaged in a statistical study of variation in this 

 form. 



Few researches have as yet been made in the spermatogene- 

 sis of Lepidoptera. Platner, in a paper published in 1886, appears 

 to have been the first to describe the development of germ cells 

 in this group of insects. Here,' however, in his plates of Pygcera 

 and Sphinx, he gave no details of chromosome numbers and 

 divisions, but figured chiefly the development of cytoplasmic 

 structures in the spermatid. Among other writers who have con- 

 cerned themselves principally with the cytoplasmic aspect of de- 

 velopment, may be mentioned Meves ('97) and La Valette ('97). 

 Munson ('06) figures a few chromosome groups in connection 

 with an extensive account of the development of achromatic 

 structures in the spermatogenesis of Papilio. Toyama's paper on 

 the silkworm I have not been able to obtain. The observations 

 of Miss Stevens, published in the past year, upon the spermato- 

 cytes of the butterflies Caccecia and Envanessa, will be referred to 



later. 



Material. 



The life history of Philosamia is, briefly as follows : The eggs 

 are laid the early part of June ; develop into larvse which pupate 

 in September, and remain in the pupal stage until their emergence 

 as moths the following June. The development of the spermato- 

 cytes takes place in the pupa. The testes are kidney-shaped 

 bodies, about one eighth inch long, lying within the body cavity 

 directly beneath the abdominal tergum. They are enveloped by 

 voluminous yellow fat bodies, from which they can be readily 

 distinguished by their lighter color, and compact shape. The 

 testis (Fig. 1) is divided into four lobes, by three thin sheets of 



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