485 
Evans and Cope ® have recently experimented upon the bactericidal 
property of milk and have reached the following conclusions: 
1. Freshly drawn milk possesses a bactericidal activity toward cer- 
tain micro-organisms and an inhibitory activity toward others. 
2. This activity is destroyed at 68° C. and materially injured at 
55° C. It varies in different cows and lasts from six to twelve hours. 
3. Coagulation and acidity of milk do not depend solely upon the 
bacterial content. They are influenced by natural properties of milk, 
which are soon overshadowed by the metabolic products of bacteria. 
4. Sterile cow’s milk freshly drawn is acid to phenolphthalein and 
increases very slowly in acidity independent of bacterial metabolism, 
due probably to the destruction of colostrum cells. 
5. Eesults obtained in testing milk with mixed bacterial florae are 
influenced by bacterial antagonism. 
Rullmann and Trommsdorff ^ state that they made a number of 
tests concerning the bactericidal properties of fresh milk. They state 
however, that unfortunately their experiments have not yet given 
them as clear a picture as they would wish of this apparently rather 
complicated phenomenon. However, they state that it seems justi- 
fiable to draw certain conclusions from their work without giving 
any of the details of the experiments. The conclusions follow: 
(1) That the bactericidal power of milk is increased when it comes 
from udders the seat of mastitis (increased secretion of serum and 
also of alexin? influence of bacteria upon the (local?) production of 
immune bodies in the milk ? ) . 
(2) That there is a direct relation between the bactericidal prop- 
erty of milk and the number of leucocytes that it contains. 
In a recent study upon the germicidal action of cow’s milk Heine- 
mann and Glenn ^ conclude as follows : 
The decrease of bacteria in fresh cow’s milk is more decided if 
fairly large numbers are inoculated than if small number only are 
present. 
The relative increase of bacteria in milk is more pronounced in 
milk heated to 75° C. or 100° C. than in raw milk or milk heated to 
56° C. 
The difference in the relative decrease in numbers of bacteria in 
milk moderately shaken and vigorously shaken is not marked if this 
shaking is done by hand. Some difference was observed, however, 
® The bactericidal property of milk, by Joseph S. Evans and Thomas A. Cope, 
University of Pennsylvania Medical Bulletin, Vol. XXI, pp. 264-274, 1908. 
^ Milchhygienische Untersuchungen, W. Rullmann and R, Trommsdorff, Archiv 
fur Hygiene, Vol. LIX, pp. 224-265. 1906-7. 
Heinemann, P. G., and Glenn, T. H. : “ Experiments on the germicidal action 
of cow’s milk,” Journ. Infec. Dis., Vol. V, pp. 534-541, Dec. 18, 1908. 
