The _epididymis_ referred to above, consists of a mass of coiled tubes and blood vessels. After the secretion passes through the tortuous coils of ciliated tubes of the epididymis, it is collected into a single tube called the _vas deferens_, which passes as a part of the spermatic cord from the scrotum, up through the groin and over the pubic arch into the pelvic cavity, passing down back of the bladder where it is slightly dilated into an _ampulla_, beyond which the duct is again contracted into a narrow tube, and the two ducts, one from either side, converge and pass into the _prostate gland_, where they empty into the _urethra_. _The seminal vesicles._--The seminal vesicles are small bladder-like organs supposed originally to contain the secreted semen collected from the testes. There are two of these vesicles, from each a small duct joins the vas deferens making up what is known as the _ejaculatory duct_. The two ejaculatory ducts coming together in the prostate gland open into the urethra. _The seminal vesicles possess glandular walls and secrete the substance which they contain, no part of the secretion of the testes normally finding its way into the vesicles._ _The prostate gland, a portion of which is homologous with the female uterus and called uterus masculinus_, is situated around the neck of the bladder and is traversed not only by the urethra (prostatic portion), but also by the ejaculatory ducts. There are numerous gland ducts which--collecting the secretion of the prostate gland--open into the urethra in the prostatic portion. Just beyond the prostate are two small glands called _Cowper's Glands_ whose ducts enter the urethra some distance beyond the prostate, at the root of the penis. 2. PHYSIOLOGY. In the treatment of the physiology of the various structures just described, we may well reverse the order of treatment, thus leading up step by step to a consideration of the more important organs. a. =Urethra.= The canal or duct of the penis is called the urethra, and it is important in considering its physiology to remember that it has not only a double function to perform, but that the performance of one function in a measure temporarily unfits it for performance of the other and makes it necessary for a special measure of preparation. The urinary excretion from the kidneys collecting in the urinary bladder is passed out periodically through the urethra. This same channel must transmit periodically secretions from the sexual apparatus. b. =Cowper's Glands= secrete only under sexual excitement, and usually they secrete only when the sexual excitement reaches a stage which induces an erection. The secretion is composed of a clear _alkaline mucus_. The purpose served in the natural economy by this alkaline mucus is a very important one and it is essential that every young man should understand it.