473 
The fact that bacterial clusters may be separated by shaking, etc,, 
is still more convincingly demonstrated in many of the other tables 
throughout the remainder of this article. 
THE GERMICIDAL ACTION COMPARED WITH THAT OF BLOOD 
SERUM. 
For the purpose of comparison the following experiment was made 
with fresh blood serum. The blood was drawn from the jugular 
vein of a horse, defibrinated and centrifugated, for fifteen minutes 
at 1,800 revolutions per minute. In this way a fresh serum free from 
fibrin and cellular elements was quickly obtained. Care was exercised 
throughout the process to avoid contamination. 
The serum was now divided into two portions: (1) Untreated, 
and (2) heated to 60° C. for twenty minutes. This temperature 
was selected as being sufficient to destroy the bacteriolytic property 
without seriously interfering with the agglutinins. 
The heated and the unheated serum was now inoculated with 
24-hour-old cultures from agar slants. The bacillary emulsion was 
first drawn in and out of a pipette in order to break up clumps. 
Bacteria per loop — 
At once 
after in- 
ocula- 
tion. 
After 2 
hours at 
37° C. 
After 4 
hours at 
37° C. 
6 hours at 37° C. 
After 24 
hours at 
37° C. 
Moder- Mixed 
ately ■with a 
shaken, 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 i 
7.600 
^ *> 70, 000 1 a *>250,000 
(°) 
B. lactis aerogenes in fresh horse serum. . 
1,500 
5 
0 
o i 0 
5,400 
B. lactis aerogenes in fresh horse serum, 
heated to 60° C. 20 minutes 
2, 640 
3,180 
9,000 | 
a *>100,000 ja*>200,000 
(a) 
a 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 
miscroscope in preparations made from the unheated serum planted 
with B. lactis aero genes. Only occasionally could the typhoid bacil- 
