276 ANIMAL PROTEINS 



is now little doubt of the value of these preparations as 

 stimulants, and it is claimed for them that they not only 

 have food value, but also that they increase the food value 

 of other foods used with them. Together with these products 

 may be classed all the miscellaneous tonic foods, in which 

 proteins are blended with carbohydrates and often also 

 with drugs. These aim at the cure of specific disorders, 

 such as nervous debility, sleeplessness, etc. Their claims 

 are often extravagant. Amongst all the multitude of 

 prepared foods, there deserve particular mention the partly 

 predigested foods. In cases where the digestive functions 

 are weak or disordered these products have been of real 

 service. 



One of the most useful and valuable of animal food 

 proteins is obtained from hen eggs. The " white " of eggs 

 is almost pure albumin, and there is much protein in the 

 yolk also. Eggs are now produced and imported by the 

 million, and form a most important item in the country's 

 dietary, the protein being in a very easily digestible form. 



It is also necessary to refer to the importance of cows' 

 milk as a source of animal food protein. The amount of 

 protein in milk (4-5 per cent.) is not large, but it is united 

 with fats, carbohydrates, salts, and vitamines in such 

 proportions, that milk is about the only article which may 

 reasonably present a claim of being a complete food. Milk, 

 moreover, forms the staple diet of infants and young- 

 children, so that its protein is certainly of great importance. 

 As an infant food, cows' milk is not altogether ideal. Even 

 when the proportions of fat, carbohydrate, and protein have 

 been adjusted to resemble human milk, there remains the 

 difficulty that some of the proteins of milk (especially the 

 casein) are too indigestible for young infants. This difficulty 

 has been only partly surmounted by those industries engaged 

 in manufacturing infant foods. Some claim to remove the 

 bulk of the casein ; others to have rendered it digestible by 

 treatment with enzymes ; others, again, simply claim to 

 supply concentrated cows' milk. Tinned milk, generally 

 concentrated to some extent, now forms a useful addition 



