COWS' MILK. 143 



Comparative Analyses of Human Milk and Cows' Milk. 



Human Milk. Cows' Milk. 



Water . . . 88.05 .86.95 



Casein and albumin 2.45 4.40 



Fat (butter) 3.40 3.65 



Lactose 5.75 4.25 



Inorganic salts 0.35 0.75 



If a comparison is made between the milk of the human being 

 and that of the cow it will be seen that cows' milk contains more 

 proteid, 4.40 as compared with 2.45 ; more fat, 3.65 to 3.40 ; and 

 more inorganic salts, 0.75 to 0.35 ; but, on the other hand, less 

 sugar, 4.25 to 5.75. It results from this that in substituting cows' 

 milk for mother's milk in the feeding of infants the milk should 

 be diluted and sugar added. 



In the consideration of the carbohydrates lactose or sugar of 

 milk was discussed, so that here we need only refer to it. As we 

 then learned, this variety does not undergo the alcoholic fermen- 

 tation with yeast, but does with some other ferments. 



The fat of cows' milk is a mixture of palmitin, stearin, and 

 olein, together with triglycerids of butyric, caproic, and other acids. 

 It also contains lecithin, cholesterin, and a yellow lipochrome. The 

 fats of human milk differ somewhat from those of cows' milk, 

 but these differences are not important. 



The proteids of milk are, as already stated, caseinogen, which 

 is by far the most important, and lactalbumin and lactoglobulin, 

 which two are present in but minute quantities. Of caseinogen 

 and its properties we have already spoken. 



It is this constituent which, when milk coagulates, becomes 

 casein, forming with fat the coagulum or curd; the liquid portion, 

 which contains whey-proteid, lactalbumin, lactose, and salts, being 

 whey. Milk is almost entirely free from purin in any form (p. 

 434). 



Cows' milk is a fluid which is very prone to undergo fermen- 

 tative changes ; one of these, the formation of lactic acid from 

 lactose, has already been described ; but there are others, which 

 are perhaps more harmful, being especially irritating to the 

 delicate mucous membrane of the alimentary canal of the young 

 infant. These changes are brought about by various bacteria 

 which find their way into the milk at the dairy, where the milk 

 is produced, or subsequently, either during transportation or after 

 it has been delivered to the customer. Great pains should be 

 taken to keep the surroundings of dairy and home in a cleanly 

 condition. 



Milk may be the transmitter of specific disease if taken from 

 a diseased animal as, for instance, one suffering from tubercu- 

 losis ; and it may also become infected after coming from the cow 

 and before it is used as food. Numerous epidemics of enteric or 

 typhoid fever have been traced to infection of the milk-supply 



