COPULATORY ORGANS 



377 



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

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

 the vas epididymitis. The vas deferens arises from the last 

 conus yasculosus, 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 {vesimlm seminahs), 

 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 or a jNIammal. 



Ho, testis ; NH, epididymi.s ; Vd, vas deferens ; A, albiiginea of the testis, wliich 

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

 the seminal tubules; Ve, vasa efferentia (rete Halleri) ; Cr, coni vasoulosi, 

 which are connected together by the collecting duct, Vrqi ; T'o, vas aberrans. 



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

 ejaculatorius. 



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 {tite.ms masculinus) , which lies embedded within 

 an accessory genital gland, the 2')rostate (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 Org^ans. 



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 

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



