mi "F THE OUTER GERM-LAYER. 



now becomes flattened until it lies in the same niveau 

 the surrounding skin. It is distinguished from the latter by 

 its r.-iM.T color, which is duo to its greater vascularity and the 

 thini 'in:-. Th.-M <l:iiing the first years 



hirth the middle *>f the glandular area, toget! the 



outlets (.Indus lartiferii. which then- O|*>M out close to one another, 

 is raised up and becomes the nipple, in the derma <>: non- 



. muscle ill i res are formed in great numbers; the remaining 

 part of the area as far as the cut is -wall becomes the areola mmm 

 The metamorphosis takes place somewhat ear > female than 



in the male. 



Soon at'ter hirth alterations take place in the still feebly developed 

 glandular tissue. There occurs a transitory swelling of the pectoral 

 glands accompanied with increased blood-pressure, and it becomes 

 possible to press out of the gland a small quantity of a milky :' 

 the so-called witches' milk. According to KOLUKER its formation is 

 due to the originally solid ducts of the glands acquiring at this time 

 a lumen 1'v the tatty degenera he central cells, which are 



dissolved, and, suspended in a fluid, are discharged from the duets. 

 According to the inve*< of BARFURTD, on the contrary, the 



so-called witches' milk of infants is the product of a genuine tran- 

 sitory secretion, and is like the real milk of the mother I- 

 morphological and chemical components. 



After birth great differences arise between the two sexes in 

 the condition of tho milk-glands. Whereas in the male the 

 glandular parenchyma remains stationary in its developu 

 in the female it begins to increase, especially at the time of 

 .-\ual maturity and Mill more after the beginning of pregiia 

 From the first-formed ducts of the glands there grow out 

 numerous lateral, hollow branches, which become covered i 

 hollow \v>icular u r hinds (alveoli) lined with a single lay< 

 evliii.lri. al i>]it helium. At the same time there are developed 

 in tho * tissue, between the separate lobules of the 



gland, numerous islands of fat-cell i onsequenoe the region 

 at \\hirh the complex of milk-glands has been formed swells into 

 a more or less prominent elevation, the mamma. 



SUMMARY. 



1. The development of the hair is inaugurated in human embryos 

 by the growing down of processes of the mucous layer of the 

 epidermis the hair-germs into the underlying derma. 



