292 AGRICULTURAL AND INDUSTRIAL BACTERIOLOGY 



tiation of horse flesh and beef in countries where both are 

 used. If some of the juice from known horse flesh is 

 injected into a rabbit a serum can be secured which will 

 always precipitate the juice from horse flesh. Similarly 

 rabbit serum may be secured specific for other kinds of 

 meat. To carry out the test some of the juice may be 

 pressed from the sample of meat suspected of being horse 

 flesh, treated with some of the serum from the immunized 

 rabbit and the identification made by the absence or pres- 

 ence of a clouding or precipitate. In a somewhat similar 

 manner the origin of blood stains has been determined. It 

 is possible to secure an antiserum which is a specific precipi- 

 tin for the blood serum of man or of any of the animals. 

 The various flours (such as wheat and buckwheat) contain- 

 ing proteins may be separated from each other by means of 

 such a test. The presence or absence of eggs in pastries may 

 also be recognized. In some cases precipitin tests may be 

 used in the recognition of disease. The blood serum of a 

 patient having typhoid fever, for example, will not only 

 agglutinate the typhoid germ but will also cause precipita- 

 tion in broth in which typhoid bacilli have been grown and 

 from which they have been filtered off. In some cases, as in 

 anthrax, the tissues suspected of coming from animals hav- 

 ing this disease may be extracted with physiological salt 

 solution and brought in contact with serum from an animal 

 which has been immunized against the particular disease. 

 The development of a precipitate shows the presence of the 

 specific organism in the tissue under investigation. 



CYTOLYSINS, INCLUDING BACTERIOLYSINS AND HEMOLYSINS 



It was first noted by Pfeiffer that the blood serum of 

 animals may sometimes possess the property of dissolving 

 or digesting bacteria. This observation was first made with 

 the organism which causes Asiatic cholera, the Vibrio 

 cholerce. It was found that when these organisms were 



