46 



Besides this, we must always consider all factors which have a 

 bearing upon the subject, remembering the phj'siology of each 

 part, and the role it plays in reproduction. Bacteria gain entrance 

 to many parts of the tract, where they multiply and probably add 

 toxic products to the seminal fluid, altering its biological char- 

 acter and resulting in partial or total destruction of the secretory 

 tissues. The testes, epididymes, vesicles, prostate, and other parts, 

 each contribute their essential part to the semen, abnormalities of 

 any one of which, as a rule, result in interferences with reproduc- 

 tion. If the vesicles are involved, we must bear in mind just what 

 is the part played by their secretion, and what is the probable 

 result if their essential elements are not added to the semen. In 

 like manner, we must consider the prostate, whose secretion stimu- 

 lates the vitality of the sperms, and adds fluid bulk to the semen. 

 Extirpation of the vesicles or prostate alone results in lowered 

 fertility, without altering the sexual desire, while removing lioth 

 glands produces total sterility. Partial or total destruction of the 

 parenchyma of either gland produces the same effect as extirpa- 

 tion, in that its function is altered or entirely absent. 



The semen should be examined, not only for the number of 

 spermatozoa and the percentage of those that are motile, but for 

 the duration and type of motion. Normal semen, when first ex- 

 amined under the microscope, shows a field closely packed with 

 highly motile spermatozoa. In every study of the semen, however, 

 we must 1)ear in mind the temperature and other conditions under 

 which it has been kept since emission. On the other hand, semen 

 from bulls of lowered fertility shows changes ranging from mild 

 disturbances such as sluggish motility and a slight decrease in the 

 number of sperms present, to aspermia, or total lack of motion. 

 Normal semen, Avhen compared with abnormal specimens, as a rule 

 presents distinct differences, either in motility, staining properties, 

 or structure of the spermatozoa. Impotent bulls, however, may 

 show at times few or no ol)servable changes in their genital organs. 

 The only assumption hei-e is that the condition probably is of 

 endocrine origin, or is some functional disturbance. Of oligo-, 

 spermia Reynolds states: ''Oligospermia, Avith normal motility 

 and vitality, is not al)so]ute sterility, l)ut is of high importance 

 because the percentage of destruction of spermatozoa during their 

 passage through the genital canal of the female is so enormous that 

 the possibility of impregnation by semen which starts out with a 

 deficient number is always poor. When the genitals of the female 

 partner are in a condition which is even moderately hostile to the 

 spermatozoa, impregnation by such semen becomes so unlikely as 

 to be not even a probability." 



Motility may be lacking in a small number, its absence may be 

 observed in a large percentage, or even in all those in the field. 

 as in necrospermia. On the other hand, the motility may be 

 sluggish or of abnormal ty])es in variable percentages. Sperms 



