204 Annals Entomological Society oj America [Vol. XII, 



After copulation, all the secretion droplets have passed from 

 the cytoplasm and this becomes still more fibrous in its nature. 

 The vacuoles persist at the tips. (Fig. 15). 



The above described metamorphosis takes place in the 

 upper two-fifths of the efferent duct. The lower two-fifths 

 is somewhat similar, though the lumen remains somewhat 

 larger, and the pseudonidi are more prominent. The middle 

 fifth of the tube remains as it was in its larval, or early pupal 

 condition, that of a thin, uniform duct, with cells cuboidal and 

 without pseudonidi. Secretion takes place in the upper portion 

 and in the lower portion of the vas deferens, but not in the 

 middle part. 



B. THE SEMINAL VESICLES. 



These organs may be considered as simply distensions of the 

 vasa deferentia; their epithelia have the same growth tendency, 

 i. e., to form pseudonidi. However, the development of the 

 pseudonidi is not carried as far as in the case of the efferent 

 ducts. At the cephalic and caudal ends of the vesicles, the 

 epithelium loses its irregular character and assumes a strict 

 columnar condition, where it graduates at one end into the 

 epithelium of the accessory glands and at the other into that of 

 the ejaculatory duct. The vesicles are chambers for the 

 retention of the semen and are not centers of secretion. This 

 latter process is localized in the vasa deferentia. 



Nussbaum (1882) originally considered the vesicles, as well 

 as the accessory glands, ejaculatory duct and penis, as 

 derivatives of the ectoderm. Others, who also have made 

 extensive studies of the reproductive system,, believe the 

 vesicles to be of mesodermal origin. At any rate, they are so 

 similar to the vasa deferentia, and sufficiently unlike the other 

 organs, to be called distentions of the former, and therefore 

 of a mesodermal nature. 



Kochevnikow (1891) found in the seminal vesicles of the 

 honey bee, two layers of muscle, an inner circular one and an 

 outer longitudinal. He could find none on the vasa deferentia. 

 In the Saturniidas, there is one layer of muscle, this is circular, 

 and is a continuation of that found on the vas deferens (Fig. 17). 



