54 REPORT OF THE No. 55 



infants under one year, but lie was strongly of the opinion that pasteurized milk 

 was very much safer than the ordinary raw milk. He brought to our attention 

 a series of experiments carried on by himself and Dr. L. E. Holt, showing the rela- 

 tive effects of pure and impure milk on infants in the tenement houses and insti- 

 tutions of New York. These experiments he summarized in part as follows : 



"During cool. weather neither the mortality nor the health of the infants ob- 

 served in the investigation was appreciably affected by the kind of milk or by the 

 number of bacteria which it contained. The different grades of milk varied much 

 less in the amount of bacterial contamination in winter than in summer, the store 

 milk averaging only about 750,000 bacteria per cc. 



"During hot weather when the resistance of the children was lowered, the kind 

 of milk taken influenced both the amount of illness and the mortality; those who 

 took condensed milk and cheap store milk did tbe wo?vt, and those who received 

 breast milk, pure bottled milk, and modified milk did the best. The effect of bac- 

 terial contamination was very marked when the milk was taken without previous 

 heating; but, unless the contamination was very excessive, only slight when heat- 

 ing was employed shortly before feeding. 



"The number of bacteria which may accumulate before milk becomes notice- 

 ably harmful to the average infant in the 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 the bacteria present the better are the 

 results. Of the usual varieties, over 1,000,000 bacteria per cc. are certainly dele- 

 terious to the average infant. However, many infants take such milk without ap- 

 parently harmful results. Heat above 170 degrees F. (77 deg. C.) not only des- 

 troys most of the bacteria present, but, apparently, some of their poisonous pro- 

 ducts. 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 deleterious. 



"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 manifest and so 

 marked that there could be no mistaking the meaning of the results. The bacterial 

 content of the milk used in the test was somewhat less than in the average milk 

 of the city. 



"No special varieties of bacteria were found in unheated milk which seemed 

 to have any special importance in relation to the summer diarrhoeas of children. 

 The number of varieties was very great, and the kinds of bacteria differed accord- 

 ing to the locality from which the milk came. None of the 139 varieties selected 

 as most distinct among those obtained, injured very young kittens when fed in 

 pure cultures. A few cases' of acute indigestion were x seen immediately following 

 the use of pasteurized milk more than thirt} r -s-ix hours old. Samples of such milk 

 were found to contain more than 100,000,000 bacteria per cc., mostly spore bearing 

 varieties. The deleterious effects, though striking, were not serious nor lasting. 



"Of the methods of feeding now in vogue, that by milk from central distri- 

 buting station unquestionably possesses the most advantages, in that it secures some 

 constant oversight of the child, and since it furnishes the food, in such a form that 

 it leaves the mother least to do, it gives her the smallest opportunity of going wrong. 

 This method of feeding is one which deserves to be much more extensively em- 

 ployed, and might, in the absence of private philanthropy, wisely be undertaken 

 by municipalities and continued for the four months, May 15th to September 15th. 



