198 Armals Entomological Society oj America [Vol. XII, 



the follicular epithelium and the testicular envelopes. It is 

 simpler to treat, first, the envelopes, and then consider 

 the epithelium, since the latter needs some explanation. 



In studying the testicular chambers, one finds that their 

 lining consists of a thin structureless membrane, which is the 

 basement membrane (Bm. — Figs. 5, 6, 7), of the follicular 

 epithelium; the distribution and function of the follicular 

 epithelium will be explained later. Outside of the basement 

 membrane is a prominent wall, which in the Lepidoptera, in 

 general, consists of two heavy layers, an inner testicular tube 

 coat (Ttc. — Fig. 5, 6, 7) and an outer capsular coat (Cc. — Fig. 

 5, 6, 7). Besides these on the periphery of the capsular coat 

 is a thin layer of material that is apparently chitinous in nature 

 and is probably due to the degeneration of tracheae, which are 

 very abundant on the testis and ramify freely over its surface. 



The Testicular Tube Coat (Figs. 5, 6, 7). Of the two layers 

 forming the wall of the testis, the inner one, or testicular tube 

 coat, is the more interesting. The coat not only surrounds the 

 entire testis but sends three partitions or septse toward the 

 hilum, forming the four chambers or testicular tubes. The cells 

 composing this layer are very peculiar. They are of meso- 

 dermal origin, and assume the appearance of true connective 

 tissue. They render the coat loose in its texture and fibrous 

 in its nature. In most cases (in Lepidoptera) the cells are 

 separated from one another, leaving large intercellular spaces 

 in which delicate cyloplasmic fibres, from the periphery of the 

 cells, ramify and anastomose. These two features give the 

 coat its loose and fibrous appearance. The shape of the cells 

 varies according to the species of insect studied. In P. cynthia, 

 they are elongated and spindle shaped, in C. promethia, they are 

 angular, less elongated, closer and have fewer cytoplasmic 

 prolongations. The cytoplasm in all cases is drawn out and 

 fibrous in nature. What is more interesting than the position 

 of the cells as to shape and texture, is their content. They are 

 apparently storage tissues, either for reserve materials or 

 for products of katabolism. In the case of the Saturniids they 

 have a prominent fat content (Fd. — Fig. 5, 6). The fat 

 globules show very plainly and beautifully in osmic acid 

 preparations. When stained with Mallory's C. T. stain, they 

 stand out as brilliant orange or orange-red droplets in the 

 pinkish cytoplasm. In Pieris, Lycaena, and species in "which 



