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infant feeding in Eochester, X. Y. His methods consisted mainly in 
education in the nursery and on the dairy farm. The clean milk 
obtained thus and distributed through milk depots resulted in lower- 
ing the death rate in children under 5 years from 33 per cent from all 
causes to 20 per cent, and now (1907) it is 15 per cent. 
Park and Holt® studied groups of infants in the tenement houses 
and institutions in Xew York for periods of about three months in 
the summers of two years (1902-3). This work is the most impor- 
tant evidence we have on the subject, for it combines careful clinical 
observation with laboratory studies. Although the number of cases 
was comparatively small, the results obtained were almost identical 
during the two summers, and indicate that even fairly pure milk, 
when given raw in hot weather, causes illness in a much larger per- 
centage of cases than the same milk given after pasteurization. A 
considerable percentage of infants, however, did apparently as well 
on raw as on pasteurized milk. Park and Holt conclude in part : 
The number of bacteria which may accumulate before milk becomes notice- 
ably harmful to the average infant in summer differs with the nature of the 
bacteria present, the age of the milk, and the temperature at which it has 
been kept. When milk is taken raw the fewer bacteria present the better are 
the results. Of the usual varieties, over 1,000,000 bacteria per cubic centi- 
meter are certainly deleterious to the average infant. However, many infants 
take such milk without apparently harmful results. Heat above 170° F. 
(77° C.) not only destroys most of the bacteria present, but apparently some of 
their poisonous products. No harm from the bacteria previously existing in 
recently heated milk was noticed in these observations, unless they had 
amounted to many millions, but in such numbers they were decidedly dele- 
terious. 
When milk of average quality was fed sterilized and raw, those infants who 
received milk previously heated did on the average much better in warm 
weather than those who received it raw. The difference was so quickly mani- 
fest and so marked that there could be no mistaking the meaning of the 
results. 
A few cases of acute indigestion were seen immediately following the use of 
pasteurized milk more than 36 hours old. Samples of such milk were found to 
contain more than 100,000,000 bacteria per cubic centimeter, mostly spore- 
bearing varieties. The deleterious effects, though striking, were not serious or 
lasting. 
After the first twelve months of life, infants are less and less affected by the 
bacteria in milk derived from healthy cattle. According to these observations, 
when the milk had been kept cool the bacteria did not appear to injure the 
children over 3 years of age at any season of the year, unless in very great 
excess. 
^ Park, Wm. H., and Holt, L. Emmett : “ Report upon the results with differ- 
ent kinds of pure and impure milk in infant feeding in tenement houses and 
institutions of New York City : A clinical and bacteriological study.” Medical 
News, vol. 83, 1903, p. 1066. 
