COPULATORY ORGANS 



377 



seminal tubules become rounded off to form the so-called coni 

 vasculosi, and these are connected together by a collecting duct, 

 the vas epididymitis. The vas deferens arises from the last 

 conus vasculosus, and gives rise towards its distal end, shortly 

 before it opens into the urinogenital sinus close to an elevation the 

 colliculus seminalis, to glandular outgrowths (vesiculce seminales), 

 which may attain a relatively enormous size in Rodents and In- 

 sectivores (Fig. 299). From this point to its termination at the 



FIG. 300. DIAGRAMMATIC SECTION OF THE TESTIS OF A MAMMAL. 



Ho, testis ; NH, epididymis ; Vd, vas deferens ; A , albuginea of the testis, which 

 gives rise to the trabeculse (t, t) and the corpus Highmori (f) ; L, L, coils of 

 the seminal tubules ; Ve, vasa efferentia (rete Halleri) ; Cv, coni vasculosi, 

 which are connected together by the collecting duct, Vep ; Va, vas aberrans. 



apex of the penis, the seminal canal is spoken of as the ductus 

 ejaculatwius. 



In many Mammals rudiments of the Miillerian ducts are pre- 

 sent in the male, and open into the urinogenital sinus. In Man, 

 only the most posterior end of the ducts remain in the form of an 

 unpaired vesicle (uterus masculinus), which lies embedded within 

 an accessory genital gland, the prostate (Fig. 299). This gland, which 

 more or less completely surrounds the urinogenital sinus, consists 

 of glandular tubules connected together by means of fibrous and 

 muscular tissue : its secretion is poured into the urinogenital sinus, 

 and is apparently of great importance in connection with the 

 activity of the spermatozoa. 



Copulatory Organs. 



Various forms of copulatory organs, morphologically distinct 

 from one another, occur amongst Vertebrates. In male Elasmo- 

 branchs a specially modified portion of each pelvic fin (clasper or 

 pteryyopodium, p. 122) serves this purpose. It consists of a series 



