ANIMAL FOOD. 283 



the other hand, it is not so suitable for full-grown persons, who 

 have not so much to form tissue as to develop heat or other force by 

 the combustion of carbon. 



The constituents of milk vary in quantity and proportion in 

 different animals, and under different circumstances in the same 

 animal. Woman's milk is, of course, the standard. Cow's rnilk 

 more nearly approximates to it than that of any other animal and 

 hence is most generally used. Cow's milk contains considerably 

 more caseine or curd, less sugar, and a little more butter than wom- 

 an's milk. When the former is substituted for the latter it should 

 be largely diluted with water and slightly sweetened. Goat's milk 

 is richer than cow's; sheep's milk still richer. Ass's or mare's milk 

 is much poorer, but much sweeter. Indeed, so large is the propor- 

 tion of sugar-of -milk in the last that it is fermented into a spiritu- 

 ous liquor, known by the name of koumiss, of value in many cases 

 of consumption, chronic bronchitis and chronic diarrhea. 



Cow's milk varies very much in quality. After calving takes 

 place the first fluid secreted differs considerably from ordinary milk, 

 and is termed colostrum; consequently cow's milk, for three or four 

 weeks after calving, is not entirely pure nor well adapted for food; 

 it has a somewhat sickly smell, and often acts as a purgative. 



The milk of the Alderney-cow is rich in butter; that of the 

 long horns is richer in curd. The milk of young cows is preferable 

 to that of old onei, and as a food for infants the age of the secre- 

 tion should be less than that of the baby; that is to say, a cow with 

 a calf two months old may do very well to feed a child of four 

 months. The milk first drawn from the cow contains less cream 

 than that which is last drawn; indeed (especially if some time has 

 elapsed between the times of milking), the amount of cream in the 

 latter may be two or three times as much as in the former. The 

 milk of the afternoon is richer both in curd and butter than that of 

 the morning. The food on which the cow is fed considerably 

 affects the quality of tne milk; poor diet impoverishes it; strong 

 vegetables, such as turnips, cabbages and onions, flavor it; decayed 

 leaves make it disagreeable; poisonous plants render it injurious; 

 nothing is equal to the fresh pasture of country -fields for securing 

 good milk. 



Its quality may be tested by the amount of cream it produces, 

 by its weight, and by its specific gravity. The larger the propor- 

 tion of cream, the better the milk. A quart of new milk, cooled, 

 should weigh about 2 Ibs., 2J ozs., if it is of fair average quality. 

 The addition of water or an excess of cream lowers the specific 

 gravity. But whether or not the milk be diluted with water, it is not 

 infrequently rendered unwholesome by being put into vessels that 

 have not been cleansed by thorough washing-out with soda. On 

 stale milk, even in minute quantities, a small blue fungus, or mould, 

 very speedily forms, which soon spreads to fresh milk and causes it 



