go. At about
the eighth month of intra-uterine existence, a good deal of this
lanugo is lost, to be replaced on the head and eyebrows by a crop of
thick, coarse, pigmented real hair. So it happens that at birth the
infant's hair is a queerly irregular growth, a mixture of what is left
of the general lanugo development, and the localized patches of the
more human hair. Until puberty this children's hair remains the same,
although at times, particularly after dentition, and after infectious
diseases which undoubtedly alter the relations of the internal
secretions, changes of color and texture occur. Then, with sexual
ripening, there appear in males the so-called terminal hairs, over the
cheeks and lips and chin, and, in both sexes, in the folds under
the shoulders and over the lower abdomen, the hair which might be
distinguished as the sex hair in contradistinction to the juvenile
hair of the head, the extremities and the back.

Now the smoothness of the face in children is connected with the
activity of the thymus and pineal glands. Among individuals in whom
the juvenile thymus persists after puberty, no growth of hair occurs
on the face, and in precocious involution or destruction of the
pineal, hair appears on the face and in other terminal regions in
children of six or less, a symptom classical in the child who suffered
from a tumor of the pineal, and discussed immortality with his
physicians. It is probable that these thymus and pineal effects are
indirect through their action upon the sex glands. For in the types
with persistent juvenile thymus there occurs a maldevelopment of the
sex glands, while in those with early pineal recession the sex glands
bloom simultanously with the appearance of adolescent hair and mental
traits. The hastening of sexual hair by tumors of the adrenal gland
may also be put down to a release from restraint of the interstitial
sex cells.

There are certain spheres in the hair geography of the body, over
which particular glands may be said to rule or to possess a mandate.
The hair of the head seems to be primarily under the control of
the thyroid. Thus in cretins reconstructed by thyroid feeding, the
straight, rather animal hair becomes lustrous and fine, silken and
curly. In the thyroid deficiency of adults, a prominent phenomenon
often is the falling out of the hair in handfuls. Baldness is
frequently associated with a progressive decrease of the concentration
of thyroid in the blood. A