610 BACTERIOLOGY OF MILK 



ination was very marked when the milk was taken without previous 

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

 when heating was employed shortly before feeding. 



"3. The number of bacteria which may accumulate before milk 

 becomes noticeably 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 the milk is taken raw, 

 the fewer the bacteria present the better are the results. Of the 

 usual varieties, over 1,000,000 bacteria per cubic centimeter are cer- 

 tainly 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, appa- 

 rently, 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 deleterious. 



'4. 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. 



"5. No special varieties of bacteria were found in unheated milk, 

 which seemed to have any special importance in relation to the summer 

 diarrhea of children. A few cases of acute indigestion were seen imme- 

 diately following the use of pasteurized milk more than thirty-six 

 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 neither serious 

 nor lasting. 



"6. After the first twelve months of life, infants are less and less 

 affected by the bacteria in milk derived from healthy cattle. Accord- 

 ing to these observations, when the milk had been kept cool, the 

 bacteria did not appear to injure the children over three years of age 

 at any season of the year, unless in very great excess. 



' 7. Since a large part of the tenement population must purchase 

 its milk from small dealers, at a low price, everything possible should 

 be done by health boards to improve the character of the general milk 

 supply of cities by enforcing proper legal restrictions regarding its 

 transportation, delivery and sale. Sufficient improvements in this 

 respect are entirely feasible in every large city, to secure to all a milk 



