668 THE HUMAN BOD '7. 



menstruation recommence about six weeks after childbirth; a 

 nursing mother usually does not menstruate for ten or twelve 

 months; the infant should then be weaned. 



When an infant cannot be suckled by its mother or a wet- 

 nurse an important matter is to decide what is the best food 

 to substitute. Good cow's milk contains rather more fats than 

 that of a woman, and much more casein ; the following table 

 gives averages in 1000 parts of milk : 



Woman. Cow. 



Casein 28.0 54.0 



Butter 33.5 43.0 



Milk sugar 44.5 42.5 



Inorganic matters 4.75 7.75 



The inorganic matters of human milk yield, on analysis, in 

 100 parts calcium carbonate 6.9; calcium phosphate, 70. 6 ; 

 sodium chloride, 9.8; sodium sulphate, 7.4; other salts, 5.3. 

 The lime salts are of especial importance to the child, which 

 has still to build up nearly all its bony skeleton. 



When undiluted cow's milk is given to infants they rarely 

 bear it well; the too abundant casein is vomited in loose 

 coagula. The milk should therefore be diluted with half or, 

 for very young children, even two thirds its bulk of water. 

 This, however, brings down the percentage of sugar and 

 butter below the proper amount. The sugar is commonly 

 replaced by adding cane sugar; but sugar of milk is readily 

 obtainable and is better for the purpose. If used at all it 

 should, however, be employed from the first ; it sweetens much 

 less than cane sugar, and infants used to the latter refuse milk 

 in which milk sugar is substituted. Cream from cow's milk 

 may be added to raise the percentage of fats to the normal, but 

 must be perfectly fresh and only added to the milk immediately 

 before it is given to the child. While milk is standing for the 

 cream to rise it is very apt to turn a little sour ; the amount of 

 this sour milk carried off with the cream is itself no harm 

 when mixed with a large bulk of fresh milk ; it carries with it, 

 however, some of the fungus whose development causes the 

 souring, and this will rapidly develop and sour all the milk it 

 is added to if the mixture be let stand. As the infant grows 

 older less diluted cow's milk may gradually be given; after 

 the seventh or eighth month no addition of water is necessary. 



In the first weeks after birth it is no use to give an infant 

 starchy foods, as arrowroot. The greater part of the starch 



