196 



Annals Entomological Society of America [Vol. XII, 



Of the parts of the reproductive system, the germ cells, the 

 ductus ejaculatorius simplex, and the penis are formed from the 

 ectoderm. The remaining organs, and the muscular covering 

 of the ductus ejaculatorius simplex are derived from the 

 mesoderm. 



Ectoderm 



Germ cells 



(Verson's Cell) ? 



Epithelium of ejaculatory duct simplex 



Penis 



Mesoderm 



Testicular coats 



(^Verson's Cell, or FoUicula repithelium)? 



Accessory glands 



Vasa deferentia 



"Ejaculatory duct duplex" 



Muscles of all the above. 



Muscles of the ejaculatory duct simplex 



The origin of the various organs, and their constituent 

 tissues has been a problem of great importance in insect 

 embryology. It is not the purpose of this paper to deal with 

 the various views set forth by embryologists, but to confine the 

 remarks to post-embryonic development. 



THE NERVES. 



The nerves innervating the reproductive organs are com- 

 plicated and deserve special mention. Their development and 

 changes occurring in them during the pupal and adult periods 

 are subjects that well deserve detailed study. Some interesting 

 features are as follows. 



In the early pupal stage (Fig. 4), the seventh abdominal 

 ganglion is closely approximated to the eighth plus tenth ganglia, 

 near the caudal portion of the seventh abdominal sternite. 

 Three pairs of nerves arise from the seventh ganglion ; these are 

 the seventh anterior, going to the seventh spiracles, the seventh 

 posterior going to the body tissue, and the seventh splanchnic 

 or sympathetic, also innervating the seventh spiracles. The 

 posterior nerve is somewhat reduced (vestigial) ; this is fre- 

 quently the case in Lepidoptera. 



The caudal ganglion, which apparently is a fusion or con- 

 densation of the eighth, ninth and tenth ganglia, gives rise to 

 three or four pairs of nerves. The most cephalic of these is the 

 eighth sympathetic, which innervates the vestigial eighth 

 spiracle. The next nerve has two branches, a long heavy one 

 (undoubtedly the eighth anterior) passes to the eighth spiracle, 



