2{)() Annals Entomological Society of America [Vol. XII, 



together to make a homogeneous cover over the entire reproduc- 

 tive gland. This layer may readily be called the tracheal 

 membrane (Tm., Figs. 5, 6, 7). 



The Follicular Epithelium. So much for the coats of the 

 testis. Each of the four tubes in each testis, is the male 

 homologue of each ovarian tube. Therefore there must be a 

 follicular epithelium. Previously it was stated that the lining 

 of each chamber consisted of a delicate basement membrane. 

 The basement membrane in all epithelia is on the ental periphery 

 of the cells. Hence, the follicular epithelium must be some- 

 where inside of the follicular chamber. Where is it and what 

 is its nature? That is the question that has puzzled a great 

 number of workers on this subject. 



Verson (1889) described a peculiar cell occurring in the 

 apical region of each testicular chamber of certain insects. 

 Other authors (La Valette St. George, Spichardt, Tischomiroff) 

 have studied this cell (called Verson's cell, Spichardt's cell, 

 la cellule geante, the apical cell, etc.), and have given various 

 interpretations as to its structure and function. 



Balbiani (1866) is probably the first to have noticed this 

 peculiar structure ; he considered it a mother cell for the sperma- 

 togonia. Spichardt (1886) regarded the element in question 

 as the primordal germ cell, forming nuclei at its periphery. 



Verson, in studying Bombyx mori, explained that this peculiar 

 gigantic cell, produced protoplasmic extensions, fibrous in 

 nature, that formed a complete mesh work throughout the 

 testicular chamber. In the meshes of this net, the sperma- 

 togonia are at first scattered, then they become collected, and 

 finally a spermatocyst or a group of germ cells surrounded by a 

 capsule, is formed. 



Verson believed, however, that the giant cell was a primordal 

 spermatogonium. Cholodkovsky (1894) upheld the view 



of Verson. 



Toyama (1894), in studying Bombyx mori, believed that 

 there occurred, in the apical portion of each chamber, an 

 invagination of the testicular wall, carrying with it an enlarged 

 and specialized cell, which later lost its connection with the 

 coat of the testis. This became the stellate cell, described 

 by Verson. It had no genetic relationship with the sperma- 

 togonia. 



