206 THE KVOLUTION OF MAK. 



of th« ordinary epidermic cells. Within this a firmer 

 central cellular mass of conical shape soon forms. This 

 increases considerably in length, detaches itself from the 

 surrounding cellular mass, the " root-sheath," and finally 

 makes its way to the outside, appearing above the outer 

 surface as a hair-stem. The deepest part, buried in the 

 skin, the hair follicle, is the root of the hair, and is sur- 

 rounded by the root-sheath. In the human embryo the 

 first hairs make their appearance at the end of the fifth 

 or in the beginning of the sixth month. 



During the last three or four months before birth the 

 human embryo is usually covered by a thick coating of deli- 

 cate woolly hairs. This embryonic wool-covering (lanugo) 

 is often lost during the last weeks of embryonic life, and, 

 at any rate, soon after birth, when it is replaced by the 

 thinner permanent hair-covering. These later permanent 

 hairs grow out of hair follicles which are developed from 

 the root-sheaths of the deciduous woolly hair. In the 

 human embryo, the embryonic woolly hair usually covers 

 the entire body, with the exception of the palms of the 

 hands and the soles of the feet. These parts remain bare, 

 just as in all Apes and most other Mammals. Not un- 

 frequently the woolly coat of the embryo differs considerably 

 in colour from the later permanent hairy covering. Thus 

 for instance, it sometimes happens in our own Indo-Ger- 

 manic race that fair-haired parents are shocked to find 

 their children, at their first appearance, covered by a dark 

 brown, or even black, woolly covering It is only after this 

 has been shed, that the parmanent fair hair, which the 

 child inherits from its parents, makes its appearance. 

 Occasionally the dark hair is retained for several weeksj 



