The opportunities afforded by a professional practice in a large city, as well as information derived from many parents and educators, have led the author of this work to believe that a great amount of suffering and crime would be avoided, did young men and those who have the charge of youth more clearly understand the nature and hygiene of the function of their sex.

It is in this department of medicine more than in any other that the unscrupulous charlatan finds a congenial field, because here he is favored by the general ignorance and the natural diffidence of his victims. Absurd and exaggerated statements have been forcibly thrust upon the public, not to allay, but to excite groundless fears. These it has been the author's aim to dispel.

On the other hand, real and serious evils result both to the individual and the community from a violation of the laws of this as of any other function. They have repeatedly been adverted to by physicians and educators, but, out of a mistaken delicacy, so vaguely that the intended warnings have been of little avail. The author, therefore, has endeavored to write in terms that cannot be misunderstood, and yet that shall not offend by want of refinement.

Fearing that he might not have accomplished this difficult task, he has submitted the advance sheets of the work to the Rev. John Todd, D. D., the eminent author of " The Student's Manual," the " Index Rerum," and other highly prized works for students; and to other distinguished educators. Their commendations have encouraged him to believe that his efforts have been successful, and that they will prove of real value to those for whom this book is designed.