156 VETERINARY BACTERIOLOGY 



and more reliable method for reaching the same end. Further- 

 more, the testing may be extended to an examination of mixed 

 meats, as sausages, and the various kinds of meat present deter- 

 mined. Specific antisera must be prepared for each of the meats 

 which it is desired to recognize by mincing the meat and soaking 

 it in physiological salt solution, j This material is then used in the 

 immunization of a rabbit by repeated injections during several 

 weeks. The flesh to be tested is likewise extracted with physio- 

 logical salt solution, the solution filtered and tested as in the blood 

 diagnosis with the various specific antisera. It will give a most 

 prominent precipitate with its homologous antiserum, and the 

 differentiation may thus be made. 



Differentiation of Bacteria. It has been found that the injec- 

 tion of the bacteria-free filtrates of liquid cultures of bacteria will 

 induce the production of an* antiserum specific for the filtrate 

 from that particular type of organism. This method is not as 

 reliable as the agglutination method of differentiating bacteria, 

 but it may be used, and is just as specific. 



Similar tests have been made to differentiate from each other 

 the proteins derived from certain plants and plant-seeds. It may 

 be stated that, in general, the injection of any protein in abso- 

 lutely pure condition will cause the production of the homologous 

 specific antiserum in the animal injected. 



