the back of the pelvis, known as the sacro-vertebral angle, becomes
better marked, and this also contributes to the development of the
characteristic female type. No doubt the female type of pelvis can be
recognised in childhood, and even before birth, but the differences of
male and female pelves before puberty are so slight that it requires
the eye of an expert to distinguish them. The very remarkable
differences that are found between the adult male and the adult female
pelvis begin to appear with puberty and develop rapidly, so that no
one could mistake the pelvis of a properly developed girl of sixteen
or eighteen years of age for that of a boy. These differences are due
in part to the action of the muscles and ligaments on the growing
bones, in part to the weight of the body from above and the reaction
of the ground from beneath, but they are also largely due to the
growth and development of the internal organs peculiar to the woman.
All these organs exist in the normal infant at birth, but they are
relatively insignificant, and it is not until the great developmental
changes peculiar to puberty occur that they begin to exercise their
influence on the shape of the bones. This is proved by the fact that
in those rare cases in which the internal organs of generation are
absent, or fail to develop, there is a corresponding failure in the
pelvis to alter into the normal adult shape. The muscles of the
growing girl partake in the rapid growth and development of her bony
framework. Sometimes the muscles outgrow the bones, causing a peculiar
lankiness and slackness of figure, and in other girls the growth of
the bones appears to be too rapid for the muscles, to which fact a
certain class of "growing pain" has been attributed.

Another part of the body that develops rapidly during these momentous
years is the bust. The breasts become large, and not only add to the
beauty of the girl's person, but also manifestly prepare by increase