The Internal Anatomy of Spiders 



In the cephalothorax, between the nervous system and the 

 body-wall, there is a layer of fat cells which appear to perform 

 a function similar to that of the urate cells of insects. 



THE REPRODUCTIVE ORGANS 



The two sexes are distinct in all Arachnida; and in each sex, 

 the reproductive organs lie in the abdomen, and open near its base. 



a. THE REPRODUCTIVE ORGANS OF THE MALE 



The testes and their ducts. — The 

 testes are situated in the anterior part 

 of the abdomen, between the ventral 

 body-wall and the longitudinal ventral 

 muscles. They are two long tubes 

 (Fig. 164, /); which are closed behind, 

 and are continued in front as two, long, 

 thin, and often much coiled sperm ducts, 

 the vasa defer entia (Fig. 164, vd). The 

 two vasa deferentia open into a common 

 pouch, the seminal vesicle (Fig. 164, sv); 

 and the seminal vesicle opens in turn 

 through a single opening on the middle 

 line of the body in the epigastric furrow. 

 The palpal organ. — There is no 

 copulatory organ directly connected with the outlet of the 

 reproductive glands; but the seminal fluid is transferred to the 

 female at the time of the pairing of the sexes by means of a 

 highly specialized appendage of the palpus of the male. This 

 organ is described in detail in the preceding chapter. 



b. THE REPRODUCTIVE ORGANS OF THE FEMALE 



The internal reproductive organs of the female consist of 

 the ovaries, the oviducts, the uterus, the vagina, and one or more 

 pouches for the reception of the seminal fluid at the time of pair- 

 ing, the spermathccce. The vagina and the spermathecae are 

 invaginations of the body-wall and, like other invaginations of 

 the body-wall, are lined with a chitinous intima, which is a con- 

 tinuation of the cuticula; while the uterus is lined with an epithe- 

 lium similar to that lining the oviducts. 



.58 



Fig. 164. DIAGRAM OF THE 



REPRODUCTIVE ORGANS OF 



THE MALE 



/, testes 8 d, vasa deferentia 



s v, seminal vesicle (after Bertkau) 



