This law of Spencer's has been discussed at length by the present writer in a previous volume,[2] and we may therefore now proceed to its notable illustration in the case of womanhood and the female sex in general, as made by Geddes and Thomson now more than twenty years ago. It is surprising that the distinguished authors do not seem to have recognized that their law is a special case of Spencer's; but one of them granted this relation in a discussion upon the present writer's first eugenic lecture to the Sociological Society.[3]

We must therefore now briefly but adequately consider the argument of the remarkable book published by the Scottish biologists in 1889, and presented in a new edition in 1900. The latter date is of interest, because it coincides with the re-discovery of the work of Mendel, published in 1865, to which we must afterwards more than once refer; and the work of the Mendelians during the subsequent decade very substantially modifies much of the authors' teaching upon the determination of sex, and the intimate nature of the physiological differences between the sexes. We have learnt more about the nature of sex in the decade or so since the publication of the new edition of the "Evolution of Sex" than in all preceding time. Such, at least, is the well-grounded opinion of all who have acquainted themselves with the work of the Mendelians, as we shall see: and therefore that book is by no means commended to the reader's attention as the last word upon the subject. The rather would one particularly direct him to the following prophetic and admirable passage in the preface of 1900:—

"Our hope is that the growing strength of the still young school of experimental evolutionists may before many years yield results which will involve not merely a revision, but a recasting of our book."

—a passage which may well content the authors to-day, when its fulfilment is so signal.

Yet assuredly the main thesis of the volume stands, and profoundly concerns every student of womanhood in any of its aspects. It will continue to stand when the brilliant foolishness of such writers as poor Weininger, the author of that evidently insane product "Sex and Character," is rightly estimated as interesting to the student of mental pathology alone. There has lately been a kind of epidemic citation from Weininger, whose book is obviously rich in characters that make it attractive to the ignorant and the many; and it is high time that we should concern ourselves less with the product of a suicidal and much-to-be-pitied boy, and more with the sober and scientific work for which daily verification is always at hand.

We cannot do better than have before us at the outset the authors' statement of their main proposition, in the preface to the new edition of their work:—

"In all living creatures there are two great lines of variation, primarily determined by the very nature of protoplasmic change (metabolism); for the ratio of the constructive (anabolic) changes to the disruptive (katabolic) ones, that is of income to outlay, of gains to losses, is a variable one. In one sex, the female, the balance of debtor and creditor is the more favourable one; the anabolic processes tend to preponderate, and this profit may be at first devoted to growth, but later towards offspring, of which she hence can afford to bear the larger share. To put it more precisely, the life-ratio of anabolic to katabolic changes, A/K, in the female is normally greater than the corresponding life-ratio, a/k, in the male. This for us, is the fundamental, the physiological, the constitutional difference between the sexes; and it becomes expressed from the very outset in the contrast between their essential reproductive elements, and may be traced on into the more superficial sexual characters."

A little further on (p. 17), the authors say:—

"Without multiplying instances, a review of the animal kingdom, or a perusal of Darwin's pages, will amply confirm the conclusion that on an average the females incline to passivity, the males to activity. In higher animals, it is true that the contrast shows itself rather in many little ways than in any one striking difference of habit, but even in the human species the difference is recognized. Every one will admit that strenuous spasmodic bursts of activity characterize men, especially in youth, and among the less civilized races; while patient continuance, with less violent expenditure of energy, is as generally associated with the work of women."

We must shortly proceed to study the origin and determination of sex, and more especially of femaleness, in the individual, and here we shall be entirely concerned with the new knowledge commonly called Mendelism, to which there is no allusion in our authors' pages. Meanwhile it must be insisted that the reader who will either read their pages for a survey of the evidence in detail, or who will for a moment consider the evident necessities imposed by the facts of parenthood, cannot possibly fail to satisfy himself that the main contention, as stated in the foregoing quotations, is correct. A further point of the greatest importance to us requires to be made.