摘要：IN BEGINNING a discussion it is usually customary to define the subject in order that there shall be no question in anyone's mind as to what is under consideration. For our purpose we shall consider general treatises and textbooks as one class, since the line of demarcation between the two is so indistinct. The definition of a textbook according to Webster is: "Any manual of instruction; a book containing a presentation of the principles of a subject, intended to be studied by the pupil and used as a basis of instruction by the teacher." We shall include here, then, books of the teaching type which includes a large variety, since the same books are not used as texts in every medical school. In most cases these books go out of date and are superseded by other texts or by other editions, for they are actually correlations of accepted basic facts and the results of recent investigations, and as such are not necessarily permanent.
