8 
BULLETIN 940, U. S. DEPARTMENT OF AGRICULTURE. 
is not positively known how the spores of the organisms giving the 
test gain entrance to milk. This fact naturally decreases the utility 
of the test. Savage recognizes this condition of affairs, and in weigh- 
ing the value of the test rightly assumes that they might gain 
entrance to milk from other sources, and thus would represent con- 
tamination by material not so undesirable as manure. 
Weinzirl seems to have overlooked the possibility of the entrance 
of the spores of B. enteritidis sporogenes from sources other than 
cow manure. He makes a further assumption, which from our 
results seems to be incorrect — that of giving an average figure which 
can be safely set up as being the number of spores per gram of 
manure. He estimates that cow manure as it enters milk contains 
the probable average of 10,000 spores per gram. He found that in 
moist cow manure there may be fewer than 730 or more than 14,300 
per gram. This is a decidedly higher figure than was obtained by 
Savage, who estimated from 10 to 10,000 per gram. As is shown 
in Table 2, our figures for the number of spores of B. enteritidis 
sporogenes in cow feces are much lower than those obtained by 
Weinzirl, and agree closely with the results of Savage. In fact, 
our figures, on the whole, are even lower than those of Savage. The 
manure examined consisted of samples ranging from fresh to nearly 
air dry, the most of them, however, being decidedly moist, 
Table 2. — Number of spores of B. enteritidis sporogenes in cow manure and feed. 
Sample 
No. 
Cow 
feces. 
Feed. 
Sample 
No. 
Cow 
feces. 
Feed. 
Silage. 
Grain. 
Silage. 
Grain. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
Spores 
per gram. 
40 
50 
200 
600 
20 
50 
600 
60 
800 
1,000 
800 
1,000 
Spores 
per gram. 
60 
10 
400 
800 
20 
55 
30 
15 
80 
40 
60 
80 
Spores 
per gram. 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
Spores 
per gram. 
140 
100 
140 
600 
20 
240 
40 
20 
20 
140 
Spores 
per grain. 
Spores 
per gram. 
30 
20 
40 
35 
10 
15 
20 
30 
100 
20 
40 
coo 

i 0-Jjj gram. 
The average spore content of 22 samples representing different 
cows from herds in widely scattered parts of the country was esti- 
mated to be 304 per gram. The number of spores was estimated 
by inoculating several series of 5 tubes of sterile milk each with a 
different dilution of manure in sterile water. The tubes were then 
heated to 80° C. for 10 minutes, then cooled and incubated. From 
