174 



BACTERIOLOGICAL METHODS 



test must not be made with a mixture of the sera of different 

 rabbits. 



Interpretation of the Results. — If in tubes i and 3 a misty cloudi- 

 ness should appear within 5 min., and if a definite precipitate forms 

 within 30 min., the other tubes remaining perfectly clear, the 

 extract is very probably one of horse flesh or the flesh of some 

 other single-toed animal. Precipitates which develop more slowly 

 cannot be considered as positive. The protein of horses and 

 donkeys cannot be differentiated by this test. In a similar man- 

 ner, tests may be made for the meat of deer, dogs or any other 

 animals, if the respective immune sera are used with the extract. 



Fig. 57. — Types of syringes; i, Roux's bacteriologic syringe; 2, Koch syringe; 

 3, Meyer's bacteriologic syringe. The Meyer syringe is the simplest and best for 

 general purposes. — {McFarland.) 



Heterologous precipitates, which occur when antisera are 

 added to concentrated foreign protein solutions, rarely are 

 disturbing factors of the tests when the above technique is used. 

 The elective absorption (according to Kister and Weichardt) 

 with the foreign protein is occasionally necessary for scientific 

 tests. 



The organoleptic tests are not always conclusive as to the 

 quahty of the meat. It is a well-known fact that the stinking or 

 putrefactive odors are generally wholly absent in even highly 

 decayed salted and brine-pickled fish and meats and in heavily 

 seasoned sausage meats and in smoked meats. On the other 



