THE ORGANS OF THE MIDDLE GERM-LAYER. 



389 



an epithelial cord. GASSER indeed observed a rudimentary canal of 

 considerable extent at the side of the vas deferens in a recently born 

 male child. Certain 

 rudiments of the ter- 

 minal portions, on 

 the contrary, are pre- 

 served even in the 

 adult individual, and 

 in descriptive anato- 

 mies are called uterus 

 masculinus (um) and 

 non-stalked hydatids 

 of the epididymis (hy) . 

 The posterior ter- 

 minal parts of the 

 two Miillerian ducts, 

 which lie close to- 

 gether enclosed in 

 the genital cord, are 

 modified into the 

 uterus masculinus 

 (um). Owing to the 

 disappearance of the 

 partition separating 

 them, they are united 

 into a single small 

 sac, which is situated 

 between the openings 

 of the two vasa de- 

 ferentia at the pro- 

 stata and therefore 

 still bears the name 

 of sinus prostaticus. 

 Extraordinarily in- 

 conspicuous in Man, 

 it acquires in many 

 Mammals, in Carni- 



fir um 



Fig. 222. Diagram to illustrate the development of the male 

 sexual organs of a Mammal from the indifferent funda- 

 ment of the urogenital system, which is diagrammatically 

 represented in fig. 219. 



The persistent parts of the original fundament are indicated 

 by continuous lines, the parts which undergo degeneration 

 by dotted lines. Dotted lines are also employed to show 

 the position which the male sexual organs take after the 

 completion of the descensus testiculorum. 



n, Kidney ; h, testis ; nh, epididymis ; pa, paradidymis ; hy, 

 hydatid of the epididymis ; si, vas deferens ; mg, degenerated 

 Miillerian duct ; um, uterus masculinus, remnant of the 

 Miillerian ducts ; gh, gubernaculum Hunteri ; hi, ureter ; 

 hi', its opening into the bladder ; sbl, vesiculae seminales ; 

 hbl, urinary bladder ; hbl', its upper tip, which is continuous 

 with the ligamentum vesico-umbilicale medium (urachus) ; 

 hr, urethra ; pr, prostata ; dej, external orifice of the ductus 

 ejaculatorii. 



The letters nk',h', si' indicate the position of the several organs 

 after the descent has taken place. 



vores and Ruminants 

 (WEBER), a considerable size, and is differentiated, as in the female, 

 into a vaginal and a uterine part. In Man it corresponds chit-fly 

 to the vagina (TOURNEUX). 



