ANTIFERMENTS. 175 



serum of an animal which has been immunized 

 with goat's milk will cause a precipitate in the 

 latter, but not in cow's milk. (See "Precipitins.") 



It has also been possible to obtain specific anti- 

 bodies for ferments: for the peptonizing ferments 

 of bacteria, for emulsin, lab, fibrin ferments, etc. 



There are, however, a great many substances for 

 which antibodies can not be obtained ; this is true 

 for substances of known chemical composition, 

 such as acids, bases, salts, and for the alkaloids 

 (strychnin, morphin, aconite, etc.) 



