MALE ORGANS OF GENERATION. 



As the sperm leaves the testicle, it consists almost entirely of sperma- 

 tozoa, crowded together in an opaque, white, semi-fluid mass, which fills 

 the vasa efFerentia, and distends their cavities. It then enters the single 

 duct which forms the body and lower extremity of the epididymis, fol- 

 lowing the long and tortuous course of this tube, until it reaches the vas 

 deferens ; through which it is conveyed onward to the vesiculae seminalis. 

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

 secreted by the walls of the epididymis and vas deferens. The vesiculse 

 seminales contain also a glairy fluid, produced by secretion from their 

 walls, which serves some secondary purpose in completing the formation 

 of the sperm. One of its functions is no doubt to dilute the mass of 

 spermatozoa, as they arrive from the testicles, and thus allow them 

 liberty of motion; as well as to increase the volume of the seminal fluid 

 and enable it to be expelled by the muscular contraction of the parts 

 about the urethra. Kolliker has found that the spermatozoa in the vas 

 deferens and epididymis are generally motionless ; and that they exhibit 

 their characteristic movements only in the vesiculse seminales and in the 

 ejaculated sperm. 



At the moment of the final evacuation of the sperm, it first passes 

 from the vesiculae seminales into the prostatic portion of the urethra, 

 where it meets with the secretion of the prostate gland, which is then 

 poured out in unusual abundance ; and farther on, there are added the 

 secretions of Cowper's glands and of the remaining mucous follicles of 

 the urethra. All these fluids increase the quantity of the sperm, and 

 serve as vehicles for the transport of the spermatozoa. 



Necessary Conditions of Fecundation by the Seminal Fluid. There 

 are several conditions which are essential to the successful accomplish- 

 ment of the act of fecundation. 



First, the spermatozoa must be present and in a state of active 

 vitality. Of all the organic ingredients, derived from different sources, 

 which go to make up the mixed seminal fluid, as discharged from the 

 urethra, it is the spermatozoa which constitute its essential part. They 

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

 secondary importance, and perform only accessory functions. 



Spallanzani 1 found that if frog's sperm be passed through a succes- 

 sion of filters, so as to separate the solid from the liquid portions, the 

 filtered fluid is destitute of fecundating properties ; while the sperma- 

 tozoa entangled in the filter, if mixed with a sufficient quantity of fluid 

 of the requisite density for dilution, may still be successfully used for 

 the artificial impregnation of eggs. It is well known that animals or 

 men, after removal of both testicles, are incapable of impregnating the 

 female, notwithstanding that all the other generative organs may remain 

 uninjured. The seminal fluid, furthermore, must be in a fresh condition, 

 so that the spermatozoa retain their anatomical characters and their 

 active movement. The experiments of Spallanzani have shown that, 



1 Experiences pour servir a FHistoire de la Generation. Gen&ve, 1786. 



