The subject dealt with in this book is one of great, and one may say growing, importance. Whether it is that the present period is one of large increase in the numbers of men and women of an intermediate or mixed temperament, or whether it merely is that it is a period in which more than usual attention happens to be accorded to them, the fact certainly remains that the subject has great actuality and is pressing upon us from all sides. It is recognised that anyhow the number of persons occupying an intermediate position between the two sexes is very great, that they play a considerable part in general society, and that they necessarily present and embody many problems which, both for their own sakes and that of society, demand solution. The literature of the question has in consequence already grown to be very extensive, especially on the Continent, and includes a great quantity of scientific works, medical treatises, literary essays, romances, historical novels, poetry, etc. And it is now generally admitted that some knowledge and enlightened understanding of the subject is greatly needed for the use of certain classes-as, for instance, medical men, teachers, parents, magistrates, judges, and the like.