Il8 IMMUNE SERA 



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 method of examina- 

 tion consists in scraping the meat and extracting it 

 with water or normal salt solution. It takes a long 

 time to extract the meat in some cases. An extract 

 is suitable for testing when it foams on being shaken. 

 If the extract is very cloudy it should be cleared by 

 filtration through a Berkfeld filter. In testing, add 

 ten to fifteen drops of antiserum to 3 cc. of the 

 saline meat extract. 



Antiprecipitins Iso-precipitins. Biologically, 

 the precipitins are found to behave like the sub- 

 stances already studied. It is possible, for example, 

 by injecting an animal with a precipitin, say 

 lactoserum, to obtain an antiprecipitin, an anti- 

 lactoserum, which counteracts or inhibits the action 

 of the precipitin. This is entirely analogous to the 

 antihasmolysins, the antispermo toxin, etc. 



If rabbits are treated with rabbit serum, a serum 

 is obtained which will, in certain cases, precipitate 

 the serum of other rabbits. This was done by 

 Schiitze, and he called this serum iso -precipitin. 



