490 MEAT AND MEAT PRODUCTS 
Sometimes clams and other shell fish contain too little liquor to make 
all of the tests above described. This is always the case when the 
shells are very small. Under these conditions the water from two or 
more shellfish shall be taken together and tested and considered 
as one. 
The English practice for the examination of oysters is somewhat 
different than that used in America. Savage (1914) has outlined the 
method which was used by Houston for the Royal Commission on 
Sewage Disposal, as follows: 
1. The outside of the oyster shells are well scrubbed with soap and 
water, and cleaned as thoroughly as possible in running tap-water, 
finally with sterile water. 
2. The hands of the investigator are thoroughly cleaned, washed in 
1 in 1000 corrosive sublimate solution, and finally with sterile water. 
3. The oysters are opened by a sterile knife held in position by a 
sterile cloth, and with the concave shell underneath. Great care must 
be taken to avoid any loss of the liquor. The liquor in the shell is 
poured into a 1000 c.c. cylinder, and the oyster and oyster liquor are 
added after the oyster has been cut into small pieces by sterile scissors. 
4, Ten oysters are treated as above in each experiment. 
5. The volume of oysters plus oyster liquor is read off, and usually 
varies between 80 and 120 c.c. For qualitative work 100 ¢.c. may, 
therefore, be taken as a fair average of the total shell contents of ten 
oysters. 
Sterile water is then poured into the cylinder up to the 1000 c.c. 
mark and the whole well stirred with a sterile rod. Each 100 c.c. of 
this liquor may be considered to contain the bacteria in one oyster. 
The Precipitin Test for the Detection of Foreign Protein in Meats. 
The food microbiologist may be called upon at any time to determine 
the presence or absence of a suspected protein in certain foods—horse or 
deer meat in sausage. The chemical methods for doing this are very 
indirect if not impossible. The bacteriological methods are very sen- 
sitive. 
Meat Extract. About 30 gms. of the meat under examination should 
be covered with 100 c.c. of sterile physiological salt solution. This is 
then allowed to stand over night in a refrigerator after which it should 
be filtered clear by any of the usual methods. Hiss and Zinsser (1914) 
advise that this should be adjusted to a neutral reaction and diluted 
with sterile water until only a slight even turbidity is formed by the 
addition of concentrated nitric acid. The less the amount of fat in the 
above protein solution, the easier will it filter. Before injection, the 
