THE REPRODUCTIVE ORGANS. 



763 



Of the Male. In order that the ovum should be fecundated, it is 

 necessary that it should meet with the seminal fluid of the male. This 

 is accomplished by the junction of the sexes in the act of coition, 

 whereby the seminal fluid is discharged into the neighborhood of, if not 

 within, the cervix uteri. Before considering the changes which are 

 produced in the ovum by impregnation, it will be as well to describe the 

 nature of the seminal fluid. This consists essentially of the semen se- 

 creted by the testes, and to this are added a material secreted by the 

 vesiculae seminales, as well as the secretion of the prostate gland, and of 

 Cowper's glands. Portions of these several fluids are discharged, to- 

 gether with the proper secretion of the testicles. 



The semen is a viscid, whitish, albuminous fluid of a peculiar odor. 

 It contains epithelium, granules or colorless particles, and large num- 

 bers of spermatozoa, which are the characteristic and essential elements. 



Fig. 459. 



Fig. 458. 



Fig. 458. Spermatic filaments from the human vas deferens. 1, magnified 300 diameters; 2. 

 magnified 800 diameters; a, from the side; 6, from above. (From Kolliker.) 

 Fig. 459. Spermatozoa. 1, Of salamander; 2, human. (H. Gibbes.) 



The spermatozoa are minute bodies each consisting of a flattened oval 

 head and attached to it a long slender tapering mobile flagellum or tail. 

 In some forms of spermatozoa there is a small middle piece interposed 

 between the head and the tail. The head is about -g-^V^th inch (about 

 4/i) long and ^i-^th inch (about 2.5^) broad. The tail is about -g-^V^th 

 to ^Vfrth inch (5//.-6/;.) long. The spermatozoa possess the power of 

 active movement, and it is by this sinuous, cilia-like movement that 

 they are propelled in the female and so helped in their progress to meet 

 the ovum. The lashing cilium-like movement of a spermatozoon may 



