486 URO-GEN1TAL APPARATUS. 



and are analogous to that from Cowper's glands and the 

 seminal vesicles. The utriculus prostaticus does not appar- 

 ently furnish a special liquid, nor take an important part in 

 the function of reproduction, but is probably only a rudi- 

 mentary organ. 



The spermatic fluid, mingling with the product of the 

 vesiculaB seminales by means of the contraction of these 

 vesiculae and of the efferent canals, arrives at the prostatic 

 portion of the urethra; here its presence, by reflex irritation, 

 sets up a mechanical action by which it is projected forcibly 

 and with jerks outside of the canal ; in other words, it is 

 ejaculated. The forcible and jerky ejaculation has been 

 generally attributed to the contractions of the bulbo-cavern- 

 ous muscle, which has been named accelerator seminis et 

 urince; but we must remember that this muscle is separated 

 from the urethral canal by the interposition of the bulbous 

 portion, rigid on account of its state of erection ; and that 

 moreover it is placed in front of the prostate, or in front of 

 the place where the spermatic fluid has been poured in ; and, 

 consequently, it is difficult to understand how it can assist 

 primarily in expelling the sperm, though it may possibly act 

 ulteriorly in completing the ejaculation of the sperm, in that 

 part which lies between the prostate and glans penis. 



At the moment that the sperm is poured into the prostatic 

 portion, this portion of the canal is isolated from the bladder 

 on account of the erection of the verumontanum (Fig. 131), 

 a little eminence situated on the posterior wall of the canal, 

 and which in its state of turgescence is in contact with the 

 anterior wall ; this would then obstruct all communication 

 between the bladder and the urethral canal, and we all know 

 that micturition is impossible during the state of erection. On 

 the other hand, the ducts, incorrectly called ejaculatory, open 

 in front of and at each side of the verumontanum, so that the 

 sperm can readily pass into the urethra, and fill up the whole 

 prostatio portion ; but it can go no farther, because at this 

 moment the so-called Wilson's muscle contracts and obliter- 

 ates the membranous portion (Fig. 131, 2). The seminal 

 fluid then accumulates in the straight part of the canal com- 

 prised between the verumontanum and the urethral sphincter, 

 or Wilson's muscle (Fig. 131, from 1 to 2) ; here it accumu- 

 lates under a high pressure, because the contractions of the 

 smooth muscles which pushed it there (efferent canal and 

 seminal vesicles), though slow, are very energetic. It cannot 

 pass towards the bladder owing to the obstruction offered by 



