1919] Riickes: Male Genital System in Lepidoptera 19o 



PARTS OF THE ADULT MALE GENITAL SYSTEM. 



In insects the male reproductive system consists of a pair of 

 testes, a vas deferens, leading from each testis into a set of 

 ducts that vary greatly in different groups of insects (Cf. 

 Berlese Gli I?isetti, Figure 1087), and a penis. The testes 

 themselves are composed of testicular tubes. These tubes may 

 be numerous or few; in the Lepidoptera there are four; the 

 tubes also may be separated (Hepialus, Fig. lA) or they may be 

 fused (Philosamia, Fig. 1 B and E, Fig. 2), and in some 

 cases the two testes may approach the median plane and fuse 

 Pieris, Fig. ID). In all cases the testicular tubes are homo- 

 logues of the ovarian tubes. In the Saturniidas the testes lie 

 in a latero-dorsal position, close to the alimentary canal, just 

 under the fifth and sixth segments of the abdomen. They are 

 reniform in shape, the convex side of each, called the apical region, 

 being mesad; the concave region known as the hilum lies ectad, 

 and is the junction of the vas deferens and the four testicular 

 tubes (Fig. 3). The vasa deferentia are long irregular tubes, 

 extending caudad to the eighth segment, where each passes 

 through the loop-hole of the tenth abdominal nerve (Fig. 4, Vd). 

 After passing through the nerve each turns cephalad to the 

 seventh segment where it unites with the seminal vesicle. 

 The seminal vesicles we may consider as distended portions of 

 the vasa deferentia, each joined anteriorly to a long convoluted 

 tube known as the accessory gland; posteriorly they unite to 

 form the upper end of the ejaculatory duct. The ejaculatory 

 duct is really in two parts; the upper end which in early pupal 

 stages may readily be seen to consist of two approximated 

 short tubes (prolongations of the seminal vesicles) is known in 

 the adult as the ductus ejaculatorius duplex; the posterior and 

 longer portion, which is an invagination of the ectoderm (it 

 bears a cuticula or chitinous lining), is known as the ductus 

 ejaculatorius simplex, and terminates in a very muscular "bulb, " 

 the bulbus ejaculatorius at the base of the penis. This last named 

 organ is the caudal extremity of the entire genital system. It is 

 wholly chitinous, bearing various types of prolongations, and 

 is connected with the body wall by means of muscles. It is 

 capable of extrusion during copulation. (The adult system is 

 figured in Fig. IE). 



