The book does not ostensibly on its title-page claim to be a work on co-education, but none the less is that the subject considered from first to last. In the preface, the author remarks in an apology for plainness of speech: "The nature of the subject which the Essay discusses, the general misapprehension both of the strong and weak points of the woman question, _and the ignorance displayed by many, of what the co-education of the sexes really means_, all forbid that ambiguity of language or euphemism of expression should be employed in the discussion." The italics are ours, but the words are Dr. Clarke's; and unmistakably show that the main drift of the book is to stem and if possible to turn the tide of popular conviction which is opening our colleges, new and old, to students, without regard to sex.[54] Again, the volume is divided into five parts, as follows, to quote the table of contents: I. Introductory. II. Chiefly Physiological. III. Chiefly Clinical. IV. Co-Education. V. The European Way. Part I. asserts that there is a difference between men and women; accuses woman of neglecting the proper care of her body; demands her physical development as a woman--not forgetting, however, on page 24, to call attention to co-education as a great and threatening danger. Part II. is, as it claims to be, physiological, and presents nothing new to the student. Part III. contains an account of seven exceptional cases of diseased action which have come under the writer's observation; a few more from another physician, and ends with this sentence: "The preceding physiological and pathological data naturally _open the way to a consideration of the co-education of the sexes._" The italics, as before, are ours. Part IV. considers the subject of co-education, already prejudged. Part V. is merely of the nature of an appendix, which attempts to show that in Europe the whole matter of woman's health is carefully watched. If the one object of the Essays is not to stay the spread of co-education, we confess ourselves unable to discover what it is. In this effort lies its only possible unity, its _primum mobile_, its one clearly defined object from beginning to end. The argument reduced, may be fairly stated thus: Boys are capable of sustained and regular work; girls are not so capable--therefore they cannot be educated together (provided the standard is kept up to the standard best for boys) without injuring the girls.