As the writer of this treatise does not propose to offer his professional services to his readers, and as even the copy-right of it is disposed of in advance, he will endeavor to present, briefly and impartially, the prominent facts which modern science has demonstrated in the phenomena of procreation, the conception and production of offspring, and the various safe and harmless methods that may be resorted to by married people to prevent child-bearing. All that is known on these interesting and important subjects is given in plain language, and with but few medical terms. In collecting this information, the writer has examined all the different modes ever recommended, discovered or invented, for the prevention of conception, whether alleged to be secret or otherwise. Some of them were found to be utterly worthless; others may, in most cases, be employed successfully by extreme caution and pains-taking, while not more than two or three are perfectly reliable. These last are subject to failure, only from prejudice or want of energy; and if adopted with moderate caution, will be successful. In these discoveries the French physicians appear to be the most ingenious, and some of the plans given are consequently of French origin. The Physiology of Generation, which comprises all medical knowledge relative to the reproduction of offspring, is a subject of intense interest to the adult portion of mankind. It has been zealously investigated by learned men of all ages—physicians, philosophers and theologians—and numerous conflicting theories have been advanced, books written, and ideas inculcated, which have presented the subject in various phases for popular reading. One class denounces all attempts to prevent conception and child-bearing as immoral, unnatural, and hurtful to health, while others hold more liberal views, and consider that married people have a perfect right to decide for themselves whether they shall breed a family or not. The writer takes no part in these arguments. He is content to impart to his readers, in a brief and matter-of-fact form, reliable physiological information which could only be obtained by long study from other sources. With this explanation, he trusts that the object of his little treatise will be appreciated by the public. THE BOOK OF NATURE. MALE GENERATIVE ORGANS.