The Sexual Life of the Child. Albert Moll
size and activity of the thyroid gland, and the lesser corpuscular richness of the blood, in women. Especially distinct are the secondary sexual characters in respect of general bodily structure. The form of the skeleton is different in the two sexes. Thus, in woman the pelvis is wider and shallower than in man. In the hair also there are notable differences: in woman the hair of the head tends to grow much longer, and woman is much less liable than man to premature baldness; the beard, on the other hand, is a masculine peculiarity. In woman the breasts attain a much greater development. The larynx is in man more prominent and longer; in woman it is wider and shallower. Woman's skin is more delicate than man's. And so on.
Now what have we to say regarding these sexual differences in the case of children? During the age which we have defined as the first period of childhood, except in the matter of the genital organs, we can detect hardly any important bodily characters distinguishing the sexes. Still, even at this early age some differences have been recorded. Thus, the average weight of new-born girls is less than that of new-born boys, the figures given by Stratz12 being, for boys, 3500 grams (7.7 lbs.); for girls, 3250 grams (7.15 lbs.). According to a very large number of measurements, the mean length of the new-born girl is somewhat less than that of the new-born boy, the difference amounting to nearly 1 cm. (⅖ths inch). Craniometric records, taken at the end of the first period of childhood, exhibit differences between the sexes; in general, the measurements show that the girl's head is smaller than the boy's in respect both of length and breadth. Further, dynamometric records, taken from children six years of age, have shown that the grasp in girls is less powerful than in boys. But if we except such differences as these, which relate rather to averages than to individuals, and which, moreover, are for the most part demonstrable only during the latter part of the first period of childhood, we find that, apart from the reproductive organs, very little difference between the sexes can be detected during the first years of life. Many investigators have been unable to confirm the assertion that even in the first year of life the hips are more powerfully developed in girls than in boys. Fehling,13 however, declares that as early as the fifth month of intra-uterine life, sexual differences manifest themselves in the formation of the pelvis. However this may be, it is beyond question that during the earlier years of the first period of childhood the differences between the sexes are comparatively trifling. But towards the end of this period, sexual differentiation becomes more marked. According to Stratz, it is at this time that the characteristic form of the lower half of the body develops. The thighs and the hips of the young girl exhibit a somewhat more marked deposit of fat than is seen in the boy of the same age. To a lesser extent the same is true of the calves. It is often assumed that even in very early childhood the sexes can be distinguished by the formation of the face. The girl's face is said to be rounder and fuller than the boy's; the expression of countenance in the former, to be more bashful and modest. Stratz, however, urges in opposition to this view, with justice, in my opinion, that we have here to do only with the effects of individual educational influences, or perhaps with individual variations, from which no general conclusions can safely be drawn.
During the second period of childhood sexual differences become much more distinct. Before considering these differences, I must say a few words regarding the growth of the child, since in this particular there exists a notable distinction between the sexes. Careful measurements have shown that during certain years of childhood growth occurs especially in height, whereas in other years the main increase is in girth. For this reason, it is customary to follow Bartels in his subdivision of each of the two periods of childhood into two subperiods. The age from one to four years is the first period of growth in girth; from the beginning of the fifth to the completion of the seventh year is the first period of growth in height; from the beginning of the eighth to the completion of the tenth year is the second period of growth in girth; and from the beginning of the eleventh to the completion of the fourteenth year is the second period of growth in height. During these periods there are certain differences in respect of growth between boys and girls. Although in general the growth in height of the boy exceeds that of the girl, there is a certain period during which the average height of girls is greater than that of boys. From the beginning of the eleventh year onwards, the girl grows in height so much more rapidly than the boy, that from this age until the beginning of the fifteenth year the average height of girls exceeds that of boys, although at all other ages the reverse is the case. In our consideration of the differences between the sexes, these differences in respect of growth must not be overlooked.
In addition to these, other important differences between the sexes manifest themselves during the second period of childhood. In the first place, it is an established fact that in the girl the secondary sexual characters make their appearance earlier than in the boy, the boy remaining longer in the comparatively neutral condition of childhood. We have seen that in the girl, at the end of the first period of childhood, the lower half of the body begins to resemble that of the woman in type. During the second period of childhood, this peculiarity becomes more marked; the pelvis and the hips widen, the thighs and the buttocks become more and more rounded; the enduring feminine characteristics in these respects are acquired. More gradually, the feminine development of the upper half of the body succeeds that of the lower; the transition from the lower jaw to the neck become less abrupt, and the face becomes fuller. The sexual difference in the growth of the hair also manifests itself in childhood. Whether cut or uncut, the girl's hair tends to grow longer than the boy's. Later, the typical development of the breasts occurs. As early as the beginning of the second period of childhood, the surface of the areola mammæ may become slightly raised; but the typical deposit of fat, leading to the hemispherical prominence of the breast, does not begin until towards the close of the second period of childhood. Even later than this is the growth of the axillary and pubic hair. Various answers are given to the question as to the relation in time between the appearance of menstruation and the development of the sexual characters just described. Unquestionably there are great differences in this respect. Whereas Axel Key declared that the secondary sexual characters appeared before the first menstruation, according to C. H. Stratz this is true only of girls belonging to the lower classes; whilst according to his own observations on girls belonging to the upper classes of society, the first menstruation precedes the development of the breasts and the growth of the pubic and axillary hair.
Concerning a number of sexual differences, during childhood, authors are not agreed. As regards the type of breathing, for instance, in the adult man, the abdominal type prevails; that is, the respiratory exchange of gases is effected chiefly by movements of the diaphragm and the abdominal muscles: whereas in the adult woman the respiration is costal, the respiratory exchange being effected chiefly by movements of the thorax. How unsettled our views are in respect of the types of respiration in children is well displayed by the collection of opinions given by Havelock Ellis.14 According to Boerhaave, sexual differences in the type of respiration were manifest even in very small children; but his observations have not been confirmed by others. Thus, Sibson states that the characteristic costal type of respiration begins in girls at the age of ten, for which reason some observers have assumed that the wearing of the corset is the cause of its appearance; others, however, among whom Hutchinson may be mentioned, deny this alleged causal connexion, stating that they have observed costal respiration in young girls who have never worn any constricting garments. Unquestionably, sexual differences in the type of respiration become apparent in the later years of childhood.
I have already pointed out that in girls the secondary sexual characters begin to make their appearance at an earlier age than in boys. In the onset of sexual differentiation, the boy thus plays a more passive part than the girl, inasmuch as he retains longer the childish type. None the less, in the boy also certain secondary sexual characters begin to develop comparatively early. Thus, in the second period of childhood, the boy's shoulders often become wider, his muscles stronger, than those of the girl. Since at the same period there occurs in girls the greater deposit of fat previously described, marked differences result in the external contours of the respective bodies. The boy's body is therefore much more angular and knobby, far less softly rounded, than that of the girl. Towards the end of the second period of childhood, an additional sexual character makes its appearance in the male sex, namely, the voice breaks. The chief remaining differences, the growth of the beard and the pubic hair, and the development of the characteristically masculine larynx, usually manifest themselves after the close of the second period of childhood—that