IPRECIPITINS. 71 



are different, and that therefore the albumin of 

 milk is not a mere transudation product, but is a 

 true secretion. Kowarski and Schiitze, as already 

 mentioned, could show a difference between vege- 

 table and animal albumin. Jess as well as Uhlen- 

 muth used the method to differentiate various kinds 

 of meat in the markets. 



The principle and the method are the same in all 

 these various applications. We treat animals with 

 the albumins which we wish to differentiate, and so 

 obtain sera specific, each for its particular kind of 

 albumin. These sera, then, produce precipitates 

 only in solutions of their respective albumins. For 

 example, if we wish to determine whether a given 

 sample of meat is horse-flesh or not we must inject 

 an animal with horse serum, or, if we prefer, with 

 an extract of horse-flesh. The serum derived from 

 this animal will then produce a precipitate in the 

 aqueous extract of the meat if this be horse-flesh, 

 but not if it be beef. Animals treated with dog 

 serum yield a serum which precipitates an aqueous 

 extract of dog-flesh, etc. The future will undoubt- 

 edly show further practical applications of this 

 method. 



Anti-precipitins Iso-precipitins. Biologically, the 

 precipitins are found to behave- like the sub- 

 stances already studied. It is possible, for exam- 

 ple, by injecting an animal with a precipitin, say 

 lactoserum, to obtain an anti-precipitin, an anti- 

 lactoserum, which counteracts or inhibits the ac- 



