530 



EMBRYOLOGY. 



buds (dg), just as at other places the sebaceous glands arise from the 

 epidermis. In the seventh month they are already well developed, 

 and radiate out below and laterally from the pit-like depression. 

 Their number increases up to the time of birth, and the larger ones 

 become covered with solid lateral buds (db). Each sprout is the 

 fundament of a milk-producing gland, which opens out on the 

 glandular area (df) by means of a special orifice ; each is morpho- 

 logically Comparable with a sebaceous gland, althouglT its function 

 has become different. 



The name glandular area is also a happily selected one 

 because it presents a point of comparison with the primitive 

 conditions of the Monotremes. For in these animals one does 



Tig. 296. Section through the fundament of the milk-gland of a female human e.tibryo 32 cm. 



long, after Hess. 

 df, Glandular area ; dw, gland- wall ; cZ<7, duct of gland ; db, vesicle of gland. 



not find, as in the higher Mammals, a sharply differentiated 

 single complex of milk-glands, but instead a somewhat depressed 

 area of the skin, even provided with small hairs, over which are 

 distributed single small glands, the secretion of which is licked 

 up with the tongue by the young, which are born in a very 

 immature state. 



In the remaining Mammals the glands, in the former case 

 opening separately upon the area, are united into a single 

 organ, which better serves the young in sucking, namely a papilla, 

 [nipple] or teat, which encloses all the outlets of the glands and is 

 grasped by the mouth of the suckling. In Man their development 

 begins after birth. The glandular area, which is encircled by 

 the cutis-wall and which before birth was depressed into a pit, 



