487 
Some of the leucocytes in milk seem to possess the power of phago- 
' • cytosis, judged by microscopic preparations. Phagocytosis, however, 
: plays no essential part in the “germicidal” action of milk, for the 
I . decrease in numbers is quite as marked in the cell-free milk as in the 
sediment rich in leucocytes. 
I The germicidal action of milk is specific. For instance, one sam- 
I pie restrained typhoid and Staphylococcus pyogenes aureus^ but not 
' paratyphoid A or B. 
I Dilution experiments demonstrate the enfeeblement of agglutinins 
J rather than the presence of a germicidal substance in solution. 
, The germicidal actions of blood and milk resemble each other in 
' some particulars. Blood serum acts more quickly and much more 
powerfully than milk. 
, Freezing milk for ten minutes and then thawing it does not affect 
I the phenomenon in question. In one experiment freezing for forty- 
eight hours did not influence its restraining action upon typhoid, but 
destroyed it for B. lactis cero genes. 
Boiling milk or heating it above 80° C. destroys its “ germicidal ” 
properties. The effect of lesser degrees of heat varies with the micro- 
organism. Thus, the restraining action for B. lactis cerogenes is 
weakened by first heating the milk at 55° C. and almost destroyed at 
60° C. ; for typhoid it is not affected by heating the milk at 60° C. 
for twenty minutes, but is materially influenced at 70° C. for thirty 
minutes. 
The “ germicidal ” action of milk varies in different animals and in 
the milk from the same animal at different times. At most, the action 
is variable and feeble. It can not take the place of cleanliness and 
ice, but may be taken advantage of in good dairy methods. 
