470 
RELATION TO AGGLUTINATION. 
Agglutination of bacteria in milk is somewhat difficult to demon- 
strate macroscopically. Under the microscope, in stained prepara- 
tions, the bacteria are in large and dense clusters in raw milk after 
standing eight hours at 37° C. In the boiled milk used as a control 
the bacteria under the same conditions appear singly or in very short 
chains or small clumps. In our work care was taken to break up all 
clumps in the suspensions used to inoculate both the raw and the 
boiled milk. | 
Vigorous shaking also gave results that plainly proved that ’ 
agglutination is one of the factors that cause an apparent decrease 
in the number of bacteria. 
The agglutinated bacterial clusters were broken asunder by one or 
both of the following methods, stated in each table : 
1. Vigorous shaking of the milk for about five minutes in a glass- . 
stoppered cylinder. 
2. Drawing the suspension in and out a number of times through a ; 
capillary pipette, the end of which is broken off square and closely ; 
applied to the bottom of a test tube. 
] 
Table No. 9. — Milk from healthy cow (Xo. 2) inoculated otie and one-half hours ] 
after milking. j| 
[Organisms from 24-hour agar cultures. Controls, same milk heated to boiling.] i 
Colonies per 
loop at once 
after inocu- 
lation. 
Colonies per 
loop after 8 
hours at 
37° C. mod- 
erate shak- 
ing. 
B- typhosus in raw milk 
5,620 
9,540 
4, 660 
4,850 
2,600 
8, 100 
17 
2, 640 
a b 1,000, 000 
3,810 
a 6 200, 000 
9,720 
a 5 1, 500, 000 
45 
B. tvphosus, control 
Staphylococcus pvogenes aureus in raw milk 
Staphylococcus pvogenes aureus, control 
B. coli in raw milk 
B. coli, control 
Original milk 
Colonies per 
loop after 8 
hours at 
37° C. after 
vigorous agi- 
tation and 
mixing with 
pipette. 
9,720 
5, 610 
a 6 100, 000 I: 
Innumerabie. 
^ About. 
