_Seminal vesicles._—The seminal vesicles have several functions. The internal secretions serve directly as an excitans of the sexual impulse. The distension of the vesicles reflectorily stimulates the sexual centres. It is a well-known fact that the distention of the vesicles in strict continence gives rise to frequent erections, just as well as the full bladder, constipation, lithiasis, and diseases of the prostate or of the rectum. The main functions of the vesicles are three in number. The vesicles serve, in the first place, as a reservoir for the testicular secretions. The other function consists in the reabsorption of the unejaculated sperma. The third function is to furnish a fluid for the dilution of the very thick testicular secretion and a medium where the spermatozoa can best carry out their motions. The seminal vesicles secrete a peculiar mucus, which is thick, fibrinous, glairy, and albuminous. This secretion constitutes the bulk of the semen. _Prostate._—The prostatic gland has a double function. It is the main point wherefrom the stimuli for the sexual impulse start. The internal secretions of the prostatic parenchyma send libidinogenous substances into the blood. The colliculus, rich in nervous elements, sends also out nervous libidinogenous stimuli. The principal function of the prostate is its secretion which imparts to the otherwise sluggish spermatozoa their lively movements. The secretion of the prostate is thin, milky, translucent, amphoteric or slightly acid. It contains the base spermin which causes the peculiar seminal odor. The secretion gives to the inert spermatozoa their peculiar motion and life. _Cowper’s glands._—The Cowper’s glands secrete a mucous albuminous fluid of alkaline reaction. The secretion takes place before the ejaculation of the semen. _Urethral glands._—The urethral glands secrete a viscid clear fluid. The secretion of these glands, together with that of Cowper’s glands, serve first as a lubricant for the walls of the urethra. The other function is to neutralize the contents covering the urethral walls. The latter are ordinarily bathed in acid urine. This acidity would harm the spermatozoa. [Illustration: CUT XXXII. _Normal sperma._ 1, Boettcher’s crystals; 2, amyloid bodies; 3, hyaline bodies; 4, testicular cells; 5, urethral epithelia; 6, lecithin bodies; 7, spermatozoa.]