Bacteria per loop — 
At and 
After 2 
hours at 
37° C. 
After 4 
hours at 
37° C. 
6 hours at 37° C. 
After 24 
hours at 
37 5 C. 
after in- 
ocula- 
tion. 
Moder- 
ately 
shaken. 
Mixed 
with a 
pipette. 
B. typhosus in fresh horse serum 
3,240 
328 
364 
220 
636 
11,000 
B. typhosus in fresh horse serum, heated 
to 60° C. 20 minutes 
2,700 
'2, 650 
7,600 
a b 70, 000 
a 6250,000 
(a) 
B. lactis aerogenes in fresh horse serum. . 
1,500 
5 
0 
0 
0 
5,400 
B. lactis aerogenes in fresh horse serum, 
heated to 60° C. 20 minutes 
2, 040 
3, 180 
9,000 
a 6100,000 
a 6200,000 
O) 
n Innumerable. 6 About. 
It is at once evident that there is a general resemblance between 
blood serum and milk so far as this phenomenon is concerned. It is 
also plain that blood has a much quicker and stronger action than 
milk. 
The results of the bacterial counts upon agar plates were confirmed 
by microscopical examination of stained smear preparations. At 
first the organisms were well distributed throughout the serum, 
whether heated or unheated. There were no clumps of over six or 
eight individuals. 
At the end of six hours no organisms could be found under the 
microscope in preparations made from the unheated serum planted 
with B. lactis aerogenes. Only occasionally could the typhoid 
bacillus be discovered in the corresponding scrum at the end of six 
hours. This agrees with the number of colonies upon the agar 
plates. 
The heated serums gave quite a different picture under the micro- 
scope. Many organisms were found, lying singly, in small and long 
chains, and in dense clusters. This corresponded to the innumerable 
growth upon the agar plates. 
RELATION TO PHAGOCYTOSIS. 
Milk contains many polymorphonuclear leucocytes and it therefore 
seems reasonable to assume that active phagocytosis takes place in 
the fresh raw product. A priori it seemed to us that this might 
account for the germicidal property of milk. This assumption was 
apparently confirmed when we found that stained smear preparations 
showed but few if any bacteria in the cells in the fresh milk just after 
inoculation with bacterial cultures, while similar preparations made 
from the same milk eight hours later, kept at 37° C., showed 
numerous bacteria in some of the cells. 
The following experiments, however, demonstrate that the ger- 
micidal power of milk is independent of its cellular contents. The 
24907— Bull. 41—08 30 
