560 MALE ORGANS OF GENERATION. 



Beside the testicles, which are, as above stated, the primary and 

 essential parts of the male generative apparatus, there are certain 

 secondary or accessory organs, by means of which the spermatic 

 fluid is conveyed to the exterior, and mingled with various secre- 

 tions which assist in the accomplishment of its functions. 



As the sperm leaves the testicle, it consists, as above mentioned, 

 almost entirely of the spermatozoa, crowded together in an opaque, 

 white, semi-fluid mass, which fills up the vasa efferentia, and com- 

 pletely distends their cavities. It then enters the single duct 

 which forms the body and lower extremity of the epididymis, 

 following the long and tortuous course of this tube, until it 

 reaches the vas deferens; through which it is still conveyed 

 onward to the point where this canal opens into the urethra. 

 Throughout this course, it is mingled with a glairy, mucus-like 

 fluid, secreted by the walls of the epididymis and vas deferens, in 

 which the spermatozoa are enveloped. The mixture is then depo- 

 sited in the vesiculae serninales, where it accumulates, as fresh quan- 

 tities are produced in the testicle and conveyed downward by the 

 spermatic duct. It is probable that a second secretion is supplied 

 also by the internal surface of the vesiculas semimiles, and that the 

 sperm, while retained in their cavities, is not only stored up for 

 subsequent use, but is at the same time modified in its properties 

 by the admixture of another fluid. 



At the time when the evacuation of the sperm takes place, it is 

 driven out from the seminal vesicles by the muscular contraction 

 of the surrounding parts, and meets in the urethra with the secre- 

 tions of the prostate gland, the glands of Cowper, and the mucous 

 follicles opening into the urethral passage. All these organs are at 

 that time excited to an unusual activity of secretion, and pour out 

 their different fluids in great abundance. 



The sperm, therefore, as it is discharged from the urethra, is an 

 exceedingly mixed fluid, consisting of the spermatozoa derived 

 from the testicles, together with the secretions of the epididymis 

 and vas deferens, the prostate, Cowper's glands, and the mucous fol- 

 licles of the urethra. Of all these ingredients, it is the spermatozoa 

 which constitute the essential part of the seminal fluid. They are 

 the true fecundating element of the sperm, while all the others are 

 secondary in importance, and perform only accessory functions. 



Spallanzani found that if frog's semen be passed through a suc- 

 cession of filters, so as to separate the spermatozoa from the liquid 

 portions, the filtered fluid is destitute of any fecundating properties ; 



