484 
dysentery bacillus, and conclude that it is evident that the much 
talked of bactericidal action of milk is of little or no aid in maintain- 
ing the low count desired in a milk used in infant feeding. 
[Since publishing our article the following additional references 
to the literature have come to our notice :] 
Coplans ° points out that two phenomena must be considered when 
organisms are transferred to a new medium. First, a period of 
latency due to change of environment (nature of food supply, reac- 
tion, and temperature). During this period of latency there is little 
or no increase in number. The second phenomenon is one observed 
in the case of fresh raw milk. It is a bactericidal inhibitory property. 
He showed that during the first six hours there is a reduction in the 
number of B. coli in raw milk, but no change in the number in boiled 
milk. At the end of twenty- four hours the increase in numbers in 
boiled milk is twenty times as great as in raw milk; at the end of 
forty-eight hours there is little difference in the numbers in raw and 
boiled milk. He holds that a given quantity of fluid can harbor only 
a certain number of organisms; therefore the number of bacteria 
planted has something to do with the rapidity of growth. 
An interesting point demonstrated by Coplans is the fact that the 
addition of enough boric acid to merely check the growth of organ- 
isms in milk abolishes all bactericidal property of the fluid. 
Moro,^ in a recent investigation, found that unfiltered raw cow's 
milk always effected a diminution in the number of colonies of B. 
typhosus during the first few hours. He believes this action is due to 
a true bacteriolytic alexin. Human milk never brought about any 
actual reduction in the number of B. typhosus^ but restrained the mul- 
tiplication as compared with the boiled milk. He found that passing 
cow’s milk through a Berkefeld filter deprived it of the power to 
reduce the number of bacteria or to restrain their multiplication. 
St. John and Pennington found that the heating of milk to 79° C. 
not only took away the power to bring about an initial decrease in 
the number of organisms, but destroyed the power to restrain the 
multiplication of bacteria throughout the period of observation, 
which was to the souring point. They call attention to the great 
care necessary in handling milk after commercial pasteurization, as 
when infected the growth of organisms is much greater than in milk 
not subjected to the process. The raw milk usually remained sweet 
twenty-four hours longer than pasteurized milk reinfected with 
organisms from the raw milk. They considered organisms only 
that were normally present in milk. 
° Coplans, Lancet, pp. 1074-1080. October 19, 1907. 
* Moro, Zeit. f. exp. Path. u. Tberap., pp. 470^79. Berlin, 1907. 
St. Jolin and Pennington, Journal of Infectious Diseases, vol 4, No. 4, pp.. 
647-656. 1907. 
