E. E. Kellogg, Science in the Kitchen
“ Cow's milk differs from human milk in that it contains nearly three times as much casein, but only two thirds as much fat and three fourths as much sugar. Cow's milk is usually slightly acid, while human milk is alkaline. The casein of cow's milk forms large, hard curds, while that of breast milk forms fine, soft curds. These facts make it important that some modification be made in cow's milk to render it acceptable to the feeble stomach of an infant. Cases are rare where it is safe to feed a child under nine months of age on pure, undiluted cow's milk. ”
