1919] Ruckes: Male Genital System in Lepidoptera 201 



LaValette St. George (1897) believed that Verson's cell was 

 simply a transformed spermatogonium (hence, a sister and 

 not a mother-cell to primary germ cells), giving forth pro- 

 longations that became the spermatocyst capsules. 



Tichomiroff (1898) probably added the most to the studies 

 of the apical cell. He definitely proved it to give rise to the 

 capsules of the spermatocysts ; it had no genetic relationship 

 with the sex cells, it gave off nuclei to the capsules, and was in 

 nature connective tissue. 



Truly, to try to understand the significance of Verson's 

 cells, from simply a study of the testes of the Lepidoptera, 

 would be very difficult and confusing. By making comparisons 

 with the structures of the testes of other insects, the true 

 homology of the apical cell may be understood. 



In most insects there is a thin, delicate layer of cells lining 

 the testicular chamber, this layer, it has definitely been shown, 

 gives rise to the spermatocyst capsule, by sending into the 

 interior of the chambers, delicate protoplasmic prolongations 

 that envelop groups of spermatogonia. This layer, frequently 

 called the cystogenous tissue, is nothing more or less than the 

 follicular epithelium of the testis, and comparable in all respects 

 with the follicular epithelium of the ovarian tubes. In the 

 Lepidoptera the state of affairs is so modified as to present an 

 apparent absence of follicular spithelium. Comparative anatomy 

 shows, however, that the capsular tissue in one case arises from 

 a definite epithelium, while in the other it arises from a single 

 enlarged apical cell. Homologizing, then, Verson's cell (Fig. 7), 

 must be a localization and reduction of the follicular epithelium, 

 playing the same role, i.e., that of nutrition, as does the epithelium 

 in the ovary. Due to this special disposition of the epithelium 

 it has lost its characteristic form and assumed a condition 

 somewhat .fibrous and similar to connective tissue. 



Most investigators have missed the significance of Verson's 

 cell, because they did not study it in stages early enough. 

 It no doubt arises from the mesoderm, as does the follicular 

 epithelium in the female, and only during embryonic develop- 

 ment can its disposition be thoroughly understood. 



In the larval stages, after all the spermatogonia have been 

 gathered into spermatocysts, the apical cell disintegrates, for' 

 it is no longer needed. The capsule of each spermatocyst can 

 readily offer all the nutriment that is needed by the growing 

 germ cells (Fig. 8). 



