PROTEIDS. — The proteids show the greatest differences, both in quantity and in character. A good average breast milk contains nearly 1.5 per cent. of pro teids, of which about one-third is casein, and the other two-thirds the soluble and easily digestible lactalbumin. Cows' milk contains nearly 4.0 per cent. of pro teids, of which four-fifths is the in soluble and difficultly-digestible casein, while only about one-fifth is lactalbu min. Stated in another way, breast-milk contains about 1.0 per cent. lactalbumin, and 0.5 per cent. of casein, while cows' milk contains only about 0.8 per cent. of lactalbumin, but 3.2 per cent. of casein. On account of the relative indi h Inv of the proteids of cows' milk, low tr pt recntages have to be used than thost breast-milk, especially for the first two or three months. During the first few days infants can rarely digest a 11 :Jiff proportion of the proteids of ct s' milk than 0.5 per cent.; by the
tnd f the first month the average Child all take 1.0 per cent., by the fourth month nearly 1.5 per cent., and by the sixth month '2.0 per cent.
It i, doubtful if cows' milk can be modified so as to make it exactly re -emble mothers' milk, for the proteids of the former differ unquestionably from those of the latter. both in quality and in quantity. The undoubted advantage, however, is that in the milk-laboratory the percentage-composition of the cows' milk can he altered to suit the idiosyn crasies of the infant's digestion, while we have far le,s control over the percentage composition of the breast-milk of the mother or NS et-nurse. Henry Ashby (Med. Chronicle, Aug., '97).