The prevailing idea concerning the treatment to which cow's milk should be subjected before feeding it to an infant has changed rapidly during the last twenty years just in proportion as our knowledge of milk and its constituents has been obtained. Twenty years ago many infants were fed on raw milk and, as the laity often remarks to us, many of these infants survived. But, as we well know, a very large proportion died; in New York at that time about one-third of all infants born died within the first year.
At that time the science of bacteriology was being developed and the bacteriologic examination of milk demonstrated a shocking contamination of this fluid with bacteria.
The great infant mortality is largely due to the summer diarrheas of infancy, and it was naturally assumed that this was probably due to the contamination of milk by bacteria and that the feeding