temperatures under 50° F. these substances act efficiently, unless the 
milk is filthy, for from twelve to twenty-four hours, but at higher 
temperatures their effect is very soon completely exhausted, and the 
bacteria in such milk will then rapidly increase. Thus the bacteria 
in fresh milk which originally numbered 5,000 per cubic centimeter 
decreased to 2,400 in the portion kept at 42° F. for twenty-four hours, 
but rose to 7,000 in that kept at 50° F., to 280,000 in that kept at 
65° F., and to 12,500,000,000 in the portion kept at 95° F. 
Park, a 1901, believes this property is too elusive to he of practi- 
cal use in dairying. 
Conn/ 1903, confirmed the fact that during the first six hours 
there is a diminution in the number of bacteria in raw milk, but 
leaves the question open whether we are dealing with germicidal 
properties in raw milk or whether the organisms are simply becoming 
more accustomed to their new medium. 
Heinemann c reported some investigations upon the subject 
which may reconcile the results of the different writers. He finds 
that for certain species of bacteria there is a bactericidal substance in 
raw milk while for other species there is none. Moreover, this germi- 
cidal property does not assert itself after the milk is from five to 
seven hours old. This power is also destroyed after heating milk to 
56° C. for thirty minutes or by bringing it to the boiling point. 
Stocking/ 1904, investigated this question by studying the multi- 
plication of certain groups of bacteria, and concluded that many of 
the species gaining access to the milk find the condition so different 
to their natural habitat that they are not able to multiply and there- 
fore they drop out very soon. On the other hand, common lactic- 
acid organisms multiply more or less rapidly and continuously from 
the start. He believes that the reduction in the number of bacteria 
during the first few hours is not the result of any germicidal condition 
or property possessed by the milk, but simply the natural dropping 
out of those species which do not find the milk a suitable medium in 
which to develop. 
Behring/ 1904, in his recent publications claims that milk has 
similar bactericidal property to that possessed by the blood. Fur- 
ther, that these bactericidal substances are rendered inactive at 60° 
C. for one hour or 50° C. in vacuo. He believes that heating milk to 
a Park, William H.: N. Y. TJniv. Bull. Med. Sci., vol. 1, 1901. 
& Conn, W. H.: Bacteria in milk and its products. London, 1903, p. 98. 
c Heinemann, Paul Gustav: The kinds of bacteria concerned in the souring of milk. 
Chicago, 1903. " 
d Stocking, W. A., Jr.: The so-called “germicidal property” of milk. Storrs Agric. 
Sta. Bull. 28, 1904, p. 89. 
e Behring, E.: Sauglingsmilch und Sauglingsterblichkeit. Therapie die Gegen- 
wart, n. s., vol. 4, 1904, p. 1-10. 
