MALE ORGANS OF GENERATION. 697 



ment of a spermatozoon is not more active than that of a bacterium 

 cell, or that of the ciliated zoospores of certain fresh-water algae. It 

 is more strictly analogous to the motion of a ciliated epithelium cell 

 when detached from its mucous membrane, which will sometimes con- 

 tinue for many hours, if kept under favorable conditions of temperature 

 and moisture. The power of movement manifested by the spermatozoa 

 also continues for a time after their separation from the rest of the body ; 

 but it is limited in duration, and after a certain interval comes to an 

 end. 



In order to preserve their vitality, the spermatozoa must be kept at 

 or near the normal temperature of the body, and preserved from the 

 contact of air or other unnatural fluids. If the seminal fluid be allowed 

 to dry, or if it be diluted by water, in the case of birds and quadrupeds, 

 or if it be subjected to extremes of heat or cold, the motion ceases, and 

 the spermatozoa soon begin to disintegrate. 



Formation of the Spermatozoa. The spermatozoa are produced in the 

 interior of certain glandular-looking organs, the testicles, which are 

 characteristic of the male, as the ovaries are characteristic of the female. 

 In man and mammalia, the testicles are solid, ovoid-shaped bodies, com- 

 posed of long, narrow, convoluted tubes, the " seminiferous tubes," some- 

 what similar to the tubuli uriniferi of the kidneys. They lie for the 

 most part closely in contact with each other, nothing intervening between 

 them except capillary bloodvessels and a little connective tissue. They 

 commence, by rounded extremities, near the external surface of the 

 testicle and pursue an intricately convoluted course toward its central 

 and posterior part. They are not strongly adherent to each other, but 

 may be readily unravelled by manipulation. 



According to the investigations of Kolliker, the formation of the 

 spermatozoa takes place within peculiar cells occupying the cavity of 

 the seminiferous tubes. As the age of puberty approaches, beside the 

 ordinary pavement epithelium lining the tubes, other cells or vesicles 

 of larger size make their appearance, each containing from one to fifteen 

 or twenty nuclei, with nucleoli. In the interior of these vesicles sper- 

 matozoa are formed; their number corresponding usually with that of 

 the nuclei. They are developed in bundles of from ten to twenty, held 

 together by the membranous substance surrounding them, but are after- 

 ward set free by the liquefaction of the vesicle, and then nearly fill the 

 cavity of the seminiferous ducts, being mingled only with a minute 

 quantity of transparent fluid. 



While in the seminiferous tubes, the spermatozoa are always inclosed 

 in their parent vesicles ; they are liberated, and mingled together, only 

 after entering the rete testis and the head of the epididymis. 



Accessory Male Organs of Generation. Beside the testicles, which 

 are the essential parts of the male generative apparatus, there are certain 

 accessory organs, by which the seminal fluid is conveyed to the exterior, 

 and mingled with various secretions which assist in the accomplishment 

 of its function. 

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