438 MILK AND MILK PRODUCTS 
Wiley and his co-workers as follows: The melted sample should be 
centrifuged for half an hour in a Stewart. lactocrite with a speed of 
approximately 3000 r.p.m. ‘This apparatus, which consists of a flat 
aluminum pan holding twenty tubes of 1 ¢.c. capacity and stoppered 
at the outer end with a specially constructed rubber plug, causes the 
sediment not only to be thrown to the end of the tube but drives it 
against the rubber plug with such a force that it is almost quantitatively 
adherent to the plug. Accordingly, if one removes the rubber stopper 
and by rubbing on a glass slide and over an area of known surface 
attaches the sediment, one can obtain, on staining and examining the 
film microscopically, an approximation of the number of organisms and 
leucocytes in 1 c.c. of the liquid. Because of the débris in the ice 
cream, which ordinarily renders the usual method of centrifuging milk 
and cream samples quite impracticable, the above method was resorted 
to so far as the detection of the presence of streptococci was concerned, 
it was found eminently satisfactory. 
Davis (1914), in connection with investigations of septic sore throat 
decided that all of the streptococci concerned were of the hemolytic 
variety. These were found to remain alive in ice cream for eighteen 
days with little diminution in numbers. He concludes that ice cream 
is a suitable medium for the growth and dissemination of dangerous 
streptococci. 
The Food and Drugs Act of the United States Department of 
Agriculture attempts to promote the production of pure. clean foods. 
With certain foods, as with ice cream, a satisfactory method of labora- 
tory control has not been worked out, and to this end more attention 
must be given to the conditions of manufacture. The Commission on 
Milk Standards has proposed the following score card by which the ice 
crcam plants may be rated. It is then assumed that there is some direct 
relation to the quality of ice cream and the conditions under which it is 
produced. 
