22 APPLIED IMMUNOLOGY 



in the blood-serum which prepare bacteria for phag- 

 ocytosis or absorption by the leucocytes. Normal 

 opsonins are present in ever}^ seruni. Opsonins which 

 are called forth by the introduction of particular bac- 

 teria are called immune opsonins or bacteriotropins. 

 They are more resistant to heat (thermostable) than 

 normal opsonins. 



{g) Antiferments. — These are antibodies which 

 resist the action of the different ferments. Owing 

 to their presence, self-digestion by the various cells of 

 the body is probably prevented. Thus for the fer- 

 ments, pepsin, trypsin, rennin, lipase, etc., we have the 

 corresponding antipepsin, antitrypsin, antirennin, 

 antilipase, etc. 



{h) Aiito-antihodies. — It has further been shown 

 that an animal can be made to form antibodies against 

 its own cells when these are introduced parenterally. 



Allergy 



To the altered condition of an animal into whose 

 tissues has been introduced an antigen or foreign cell 

 product, von Pirquet has given the term allergy. 

 Under allergic phenomena are therefore included all 

 subsequent reactions on the part of the body as a re- 

 sult of the parenteral introduction of foreign protein 

 materials, i.e., introduction by other channels than 

 through the gastro-intestinal tract. An animal thus 



