Milk and eggs play comparable parts in the economy of nature. They serve as the sole sources of nutriment to certain types of developing organisms at a period when almost all tissues are experiencing a rapid growth. It might be anticipated, therefore, that each of these biologic products contains a notable complement of the various nutrient factors that are essential to the growing organism. This involves not merely sources of energy like the fats and carbohydrates, indispensable nitrogenous precursors of the production of proteins, and the essential body components of an inorganic sort, but also the as yet less tangible requisites represented by the various vitamins.
The significance of milk in human nutrition beyond the stage of infancy is becoming adequately recognized. Its growing popularity is reflected in the increasing sales of fluid milk. The per capita consumption in New York, for example, in 1926 was 139 quarts, or 39