384 MILK AND MILK PRODUCTS 
Dirt or Sediment in Milk. The cstimation of dirt in milk has been 
regarded by many as a reliable index of milk quality. Most attention 
has been given to insoluble dirt or that which may be removed from the 
milk by some mechanical means. Schroeder (1914) has given a résumé 
of the different methods of determining dirt in milk. He stated that the 
amount of dirt in fresh milk approximates the number of bacteria. This 
was borne out by the work of Reed and Reynolds whose data bearing 
on this question have been presented in Table XLI. Campbell (1916) 
carried out an interesting study on the relation of the number of bac- 
teria to the amount of dirt and stated that the amount of dirt which 
appeared on the disks was no criterion of the number or kind of bacteria 
in the milk. Ayers, Cook and Clemmer (1918) found that*the “ sedi- 
ment test bore a somewhat close relation to the number of bacteria in 
fresh, unstrained milk handled in sterilized utensils.”” The kind of dirt 
is, of course, important in this connection. Cow dung would probably 
be an objectionable type. Ayers and his colleagues, however, state 
that cow dung (fresh) “‘ though an important source of contamination in 
general, is not so great a factor as unsterilized utensils in causing high 
bacterial counts.” Kinyoun (1914) regards cleanliness in production 
as the most important factor in milk hygiene. From an examination 
of 3000 samples of milk he states that in good milks, there is 1 colon 
bacillus to every 50,000 bacteria while in dirty milk the ratio is 1 to 555. 
Taste XLI 
RELATION BETWEEN THE AMOUNT OF DIRT IN MILK AND THE 
BACTERIAL CONTENT 
(After Reed and Reynolds) 
Amount of Dirt m 100 ¢.c. of Muk. utmber of Bacteria Milk. 
LO milligrams... occ ce cc cette eee eee 4,833 
2D milligrams 2... ce ce cee cee eee nees 6,750 
B30 milligrams 2.1... cee ec cece teen eens 12,000 
4O milligrams 2.1... ... cece cece eee e eens 17,625 
5O milligrams ........ cece ccc eee cere e ee eeees 18,375 
100 milligrams. ... ce ec cece tent e aes 32,875 
a, 
The available data seem to indicate that milk may be produced 
under decidedly filthy conditions and yet have a low bacteria content. 
The utensils seem to be the contributing factor. These data should 
not be taken to prove that barns may be kept dirty. Milk, which is 
produced in dirty plants, is more liable to contain dirt; this dirt may be 
