THE MILK. 



333 



surfaces of the cornea and conjunctiva moist and polished, and to 

 preserve in this way the transparency of the parts. The tears, 

 which are constantly secreted, are spread out uniformly over the 

 anterior part of the eyeball by the movement of the lids in wink- 

 ing, and are gradually conducted to the inner angle of the eye. 

 Here they are taken up by the puncta lachrymalia, pass through 

 the lachrymal canals, and are finally discharged into the nasal pas- 

 sages beneath the inferior turbinated bones. A constant supply of 

 fresh fluid is thus kept passing over the transparent parts of the 

 eyeball, and the bad results avoided which would follow from its 

 accumulation and putrefactive alteration. 



5. THE MILK. The mammary glands are conglomerate glands^ 

 resembling closely in their structure the pancreas, the salivary, and 

 the lachrymal glands. They consist of numerous secreting sacs or 

 follicles, grouped together in lobules, each lobule being supplied 

 with a common excretory duct, which joins those coming from 

 adjacent parts of the gland. 



(Fig. 105.) In this way, by Fig. 105. 



their successive union, they 

 form larger branches and 

 trunks, until they are reduced 

 in numbers to some 15 or 20 

 cylindrical ducts, the lactifer- 

 ous ducts, which open finally 

 by as many minute orifices 

 upon the extremity of the 

 nipple. 



The secretion of the milk 

 becomes fairly established at 

 the end of two or three days 

 after delivery, though the 

 breasts often contain a milky 



fluid during the latter part of pregnancy. At first the fluid dis- 

 charged from the nipple is a yellowish turbid mixture, which is 

 called the colostrum. It has the appearance of being thinner than 

 the milk, but chemical examinations have shown 1 that it really con- 

 tains a larger amount of solid ingredients than the perfect secre- 

 tion. When examined under the microscope it is seen to contain, 

 beside the milk-globules proper, a large amount of irregularly glo- 



1 Lehmann, op. cit., vol. ii. p. 63. 



GLANDULAR STRUCTURE OF MAMMA. 



