It will be remembered that the male urethra affords passage not only for the urine, but also for the generative products. The urine is acid in reaction and the frequent passage of urine along the urethra leaves that duct acid in reaction under usual conditions. The spermatozoa are very sensitive to acid and their vitality is seriously impaired by acid of any kind, particularly the acid of the urine. Nature has provided that the secretion from Cowper's glands should precede the generative products along the urethra, thus neutralizing the acid and insuring for the spermatozoa an alkaline passage from the body. Besides this important function of the secretion from Cowper's glands, the slimy transparent mucus appearing at the glans penis under sexual excitement serves as a natural lubricant covering the glans of the male organ. A secretion from the female similarly prepares her organs for sexual contact so that the delicate mucous membrane, particularly of the female organs, shall not suffer abrasion. Many young men have experienced the appearance of the secretion from Cowper's glands and wholly misunderstanding its nature have feared that they were losing some vital fluid. This misunderstanding of the nature of this fluid makes the young man especially subject to the misrepresentations of the advertising quack and charlatan who allege that he is losing vital fluid and will, if not treated, undergo general debility and loss of procreative power. This brief explanation of the significance of the secretion of Cowper's glands will protect the young man from any such misrepresentations. c. =The Prostate Gland.=--That the prostate gland is intimately associated with reproduction is evident from the fact that in those male animals that have suffered castration before puberty, the prostate gland withers and practically disappears. What then is the role that this gland plays? Like Cowper's glands, it secretes only during sexual excitement. Under such excitement its ducts become gorged with a secretion peculiar to it and at the moment of the emission or the ejaculation of the semen the numerous ducts empty their contents into the urethra to be mingled with and made a part of the semen. The secretion of the prostate is composed of a watery solution of protein and of alkaline salts and so closely similar to the secretion of the seminal vesicles that we will consider its action along with that of the secretion from the vesicles. d. =The Seminal Vesicles.=--_The seminal vesicles secrete continuously._ The secretion is composed of an aqueous solution of albumin and of alkaline salts. This secretion together with the secretion from the prostate gland is poured into the urethra at the moment of sexual orgasm; they become mixed in their transit through the urethra with the secretion from the testes. This mixture is known as semen. [See pg. 42.]