INTEGUMENT 



39 



The mammalian skin is usually rich in glands which are of two 

 types, tubular and acinous (p. 23). To the first belong the sweat 

 glands, which extend from the Malpighian layer, where they arise, 



©©,©© ©©•©© <%•# 



©•%® 



©..© %.^© 



"©•© 



'© 







Fig. 30. — ^, arrangement of the two kinds of hair in Ornithorhynchus; B, Arrange- 

 ment of hair in Ptilocerus lori, with the probable relation of the hair to the ancestral 

 scales; both after Meijere. 



down through the corium and then are coiled in order to obtain 

 greater length. The acinous glands are represented by the sebaceous 

 ilands in connexion with each hair (fig. 29, g), and by the scent 

 ilands in the anal or inguinal region of many carnivores, rodents and 



Fig. 31. — Arrangement of the hairs in groups of threes and fives in the human embryo, 

 with the probable ancestral arrangement of the scales, after StOhr. 



edentates. Others may occur in very diverse regions, as on the face 

 ^bats, deer), in the occipital (camel) or temporal region (elephant), 

 ')r on the legs (swine). 



