DEVELOPMENT OF CITY MILK SUPPLY PROBLEMS 39 
marked improvement in the health of ailing infants when fed 
upon sour milk is commonly attributed to a difference in the 
kinds of germs present in the milk consumed before and after 
the improvement with a corresponding difference in the 
character of the changes produced in the milk by these germs. 
So far as studies have been made, there is shown surpris- 
ingly little qualitative difference in the bacterial flora of the 
ordinary public milk supply when carrying a high germ con- 
tent and the flora of the milk which has acknowledged ther- 
apeutic value in the treatment of sick babies. There are, of 
course, quantitative differences in that the total number of 
germs in the therapeutic milk is much higher and this in- 
erease in numbers is largely in germs with marked acid-form- 
ing tendencies. 
Too little is yet known of the chemical products of bacterial 
action in milk to justify conclusions, but the known ability 
of milk compounds to absorb or otherwise neutralize small 
amounts of bacterial by-products suggests that many of them 
may be cared for in this way. Acid is the most evident by- 
product of this bacterial action but this is most abundant in 
the therapeutic milks. 
Failing to find a satisfactory explanation for the illness of 
children in the number of germs involved or in any of their 
recognizable by-products, it seems logical to seek for other 
explanations of the constantly observed coincidence of high 
germ content milk supplies and baby sickness. 
A part of the diarrheal diseases of children is undoubtedly 
due to the action of specific dysentery organisms. No tech- 
nique is available by which the presence of these organisms 
in milk can be readily determined but pasteurization offers 
the same protection against them as against other pathogenic 
organisms. 
Experience in the feeding of domestic animals has abun- 
dantly demonstrated that an animal accustomed to a uniform 
dict is markedly disturbed by sudden changes in its ration. 
It ig an axiom in the feeding of dairy cows that changes in 
the amount or character of their ration should be made 
gradually. The gratifying improvements which have followed 
