It is impossible to discuss, as we might well do, the available evidence as to the effect of external activities upon that wonderful function of womanhood which, in its correspondence with the rhythm of the tides, hints, like many other of our attributes, at our distant origin in the Sea--the mother of all living. Reference was made in an earlier chapter to this function, and its use as, in most cases at any rate, a criterion of womanhood and a gauge of the effect of physical exercise or mental exercise thereupon. The writer of "Women and Economics" has nothing to say on this subject--less, if possible, than on the subject of lactation. The menstrual function would admirably and fundamentally illustrate the present contention, but it will be better to take the great maternal and mammalian function of nursing as a criterion of womanhood, and as a test of the contention that the more freely the mother works as do the savage woman and the peasant woman, the more rightly she fulfils the "primal physical functions of maternity." Before we consider the actual evidence (and Mrs. Gilman does not deal at all in evidence on these fundamentals to her argument) let us meet the argument about the "savage woman," who works as hard as men do,--though much less hard than early observers of savage life supposed--and who is nevertheless a successful mother. It is completely forgotten that, just as parenthood, both fatherhood and motherhood, demands more of the individual as we rise in the scale of animal evolution, so, within our own species, the same holds good. In general, the mothers of civilized races are the mothers of babies whose heads are larger at birth (as they will be in adult life), than those of savage babies. It is true that the civilized woman has, on the average, a considerably larger pelvis than that of, for instance, the negress. There must be a feasible, practicable ratio between the two sets of measurements if babies are to enter the world at all. But the increasing size of the human head is a great practical problem for women. No one can say how many millions have perished in the past because their pelves were too narrow for the increasing demands thus made upon them, and doubtless the greater capacity of the female pelvis in higher races is mainly due to this terrible but racially beneficent process of selection, by which women with pelves nearer (e. g.) to negro type, have been rejected, and women with wider pelves have survived, to transmit their breadth of pelvis to their daughters and carry on the larger-headed races. But even now obstetricians are well aware that the practical mechanical problem for the civilized woman is much more serious than for her savage sister; and the argument that civilized women would discharge maternal functions as well as savage women if they worked as hard is therefore worthless.