By) BULLETIN 642, U. S. DEPARTMENT OF AGRICULTURE. 
ent m the milk drawn directly from the udder. It was not found 
for the reason that the bacterial count being so great such dilutions 
had to be used in plating that the small number of bacteria of that 
type did not appear on the plates. It is also of interest to note that 
the washings from the unsterilized cans contained high percentages 
of the alkali-forming bacteria and particularly the peptonizing 
group. The addition of peptonizing bacteria in large numbers to 
milk is a matter of considerable importance, since they may be highly 
undesirable in that they produce putrefactive changes. North has 
frequently called attention to the importance of the use of sterilized 
utensils, which has been further emphasized by results obtained by 
Prucha, Harding, and Weeter (8). The work of these investigators 
and our own experiments indicate clearly that the use of sterilized 
utensils is the greatest factor in the production of milk of low bac- 
terial count. 
TABLE 14.—Bacterial groups in milk directly from the udder, in fresh milk from 
sterilized and unsterilized utensils, and in washings from clean but unsteril- 
ized cans, 
Bacterial groups. 
Number | i 
Source of sample. of samples es | = Acid co- 
averaged.| Acid co- | | are epto- | agulating 
agulating Acid. Inert. Alkali. | nizing. (pept 5 
| nizing). 
5 gee J HiTech ae cr | 
Per cent.| Per cent.| Per cent.| Per cent.| Per cent.| Per cent. 
Wid der nays ants OS Ue eae se 47 46. 21 37.25 9.41 0.45 1.36 5.09 
Milk from sterilized utensils. ... 19 25. 81 39. 22 25. 51 5 ffl 3. 26 5.49 
Milk from unsterilized utensils. . iy; 11.54 16.99 31.55 14.14 25. 79 0 
Washings from unsterilized cans_ 2 -39 2185 11. 64 19. 24 66. 87 0 
The small dairyman often has difficulty in providing an inex- 
pensive apparatus for sterilizing his utensils. Realizing this, a sim- 
ple steam sterilizer has been devised in the Dairy Division. The 
sterilizer, fully described in Farmers’ Bulletin 748, entitled “A Sim- 
ple Steam Sterilizer for Farm Dairy Utensils,” is inexpensive to 
construct and operate and provides a practical method for sterilizing 
dairy utensils on a small scale. The bulletin will be sent free to 
anyone on request to the Department of Agriculture. 
CONTAMINATION OF MILK BY MANURE AND DIRT. 
It has been shown that unsterilized utensils are a source of very 
great contamination of milk, but they are not the only means of con-" 
tamination. Statements have been made, and possibly it has been the 
general belief, that the greatest contamination of milk comes from 
manure and other accumulations of dirt on the body of the cow. 
The results in these experiments indicate that while that is an im- 
portant source of contamination from the standpoint of the number 
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