MAMMARY GLANDS. 343 



some common salt and 50 cubic centimetres concentrated sulphuric acid, and allow B to flow 

 from a burette into this mixture until a faint green colour is obtained. The number of cubic 

 centimetres of B used correspond to 1 milligramme of nitric acid. 



Twenty-five cubic centimetres of the water to be investigated are mixed with 50 cubic centi- 

 metres of concentrated H 2 S0 4 , and titrated with B until a green colour is obtained. This process 

 must be repeated, and on the second occasion the solution B must be allowed to flow in at once, 

 when usually somewhat more indigo solution is required to obtain the green solution. The 

 number of cubic centimetres of B (corresponding to the strength of B, as determined above) 

 indicates the amount of nitric acid present in 25 c.cmtr. of the water investigated. As much 

 as 10 milligrammes nitric acid have been found in spring water {Marx, Trommsdorff). 



Sulphuretted Hydrogen is recognised by its odour also by a piece of blotting-paper moistened 

 with alkaline solution of lead becoming brown, when it is held over the boiling water. If it 

 occurs as a compound in the water, sodium nitro-prusside gives a reddish-violet colour. 



It is of the greatest importance that drinking water should be free from the presence of organic 

 matter in a state of decomposition. Organic matter in a state of decomposition, and the 

 organisms therewith associated, when introduced into the body, may give rise to fatal maladies, 

 e.g., cholera and typhoid fever. This is the case when the water supply has been contaminated 

 from water which has percolated from water-closets, privies, and dung-pits. The presence of 

 organic matter may be detected thus (1) A considerable amount of the water is evaporated to 

 dryness in a porcelain vessel, if the residue be heated again a brown or black colour indicates the 

 presence of a considerable amount of organic matter ; and if it contain N, there is an odour of 

 ammonia. Good water treated in this way gives only a light brown stain. The presence of 

 micro-organisms may be determined microscopically after evaporating a small quantity of the 

 water on a glass slide. (2) The addition of potassio-gold chloride to the water gives a black 

 frothy precipitate after long standing. (3) A solution of potassium permanganate, added to the 

 water in a covered jar, gradually becomes decolorised, and a brownish precipitate is formed. 



"Water containing much organic matter should never be used as drinking water, and this is 

 especially the case when there is an epidemic of typhoid fever, cholera, or diarrhoea. In all 

 such circumstances, the water ought to be boiled for a long time, whereby the organic germs 

 are killed. The insipid taste of the water after boiling may be corrected by adding a little 

 sugar or lime juice. 



230. THE MAMMAEY GLANDS AND MILK Milk Duct About 20 galactoferous ducts 

 open singly upon the surface of the nipple. Each of these, just before it opens on the surface, 

 is provided with an oval dilatation the sinus lacteus. When 

 traced into the gland, the galactoferous ducts divide like the 

 branches of a tree, and a large branch of the duct passes to each 

 lobe of the gland, all the lobes being held together by loose 

 connective-tissue. Only during lactation do all the fine ter- 

 minations of the ducts communicate with the globular glandular 

 acini. Every gland acinus consists of a membrana propria, sur- 

 rounded externally with a network of branched connective-tissue 

 corpuscles, and lined internally with a somewhat flattened poly- 

 hedral layer of nucleated secretory cells (fig. 233). The size of 

 the lumen of the acini depends upon the secretory activity of 

 the glands ; when it is large, it is filled with milk containing 

 numerous refractive fatty granules. The walls of the milk ducts Y\<*. 233. 



consist of fibrillar connective-tissue, some fibres are arranged ^cirri f themammary o-land 

 longitudinally, but the chief mass are disposed circularly, and of a sh duri lactation, 

 are permeated externally with elastic fibres, while in the finer a mem b rana propria b 

 ducts there is a membrana propria continuous with that of the secretory epithelium ' ' 

 gland acini. The ducts are lined by cylindrical epithelium. * * 



During the first feiv days after delivery, the breasts secrete a small amount of milk of greater 

 consistence, and of a yellow colour the colostrum in which large cells filled with fatty 

 granules occur the colostrum-corpuscles (fig. 235). Sometimes a nucleus is observable within 

 them, and rarely they exhibit amoeboid movements (fig. 234, c, d, e). The regular secretion 

 of milk begins after three to four days. It was formerly supposed that the cells of the acini 

 underwent a fatty degeneration, and thus produced the fatty granules of the milk. It is more 

 probable, from recent observations, that the cells of the acini manufacture the fatty granules, 

 and their protoplasm eliminates them, at the same time forming the clear fluid part of the milk. 



Changes during Secretion. Pratscb and Heidenhain found that the secretory 

 cells in the non-secreting gland (fig. 234, I), were flat, polyhedral, and uni- 

 nucleated, whilst the secreting cells (fig. 234, II) often contained several nuclei, were 

 more albuminous, higher, and cylindrical in form. The edge of the cell directed 

 towards the lumen of the acinus undergoes characteristic changes during secretion. 



