THEORIES OF IMMUNITY 193 



The digestive substances normally produced by the organ- 

 ism are normal antibodies. 



The excess antibody found in the blood and in the fluids 

 of an immunized anaphylactized organism, is the excess of 

 one of the digestive substances of which the whole constitutes 

 the normal antibody. The excess antibody found in the 

 serum of immunized animals is a substance which contributes 

 to the digestion of the corresponding antigen, without being 

 able in itself to finish this operation. 



Reactions between antibodies and antigens are specific, 

 but are not always exclusively so. 



Thanks to the antibodies in excess, the organism will 

 digest more easily and more rapidly antigens which have 

 determined the excess of these antibodies and the results 

 will be : 



1 . A certain degree of anti-infectious or antitoxic immunity 

 in those cases where the antigen is a germ which is patho- 

 genic by its albumin or by its toxin. 



2. A certain chronic morbid state determined by the 

 functional insufficiency of the organs assigned to the pro- 

 duction of the excess antibodies, and lasting as long as the 

 overproduction of the antibodies. 



3. Anaphylactic crises more or less acute and serious, 

 whenever a new and sufficient dose of antigen will suddenly 

 combine with the excess antibody and form a precipitate. 



Thus acquired anti-infectious immunity consists in the 

 ability to digest a certain dose of infectious germs before 

 these germs have had time to multiply so as to become patho- 

 genic; and the organism acquires this property by producing 

 a series of intracellular and extracellular digestive ferments. 

 One of these ferments is the excess antibody. 



The first phase of this digestion, that is, the combination 

 between the antigen and the excess antibody, occurs there- 

 fore outside the cells, in the fluids of the organism. If the 

 quantity as well as the quality of the antigen is such as to 

 form an abundant precipitate with the antibody, the defen- 

 sive act of the organism, the neutralization of the infectious 

 agent, will be accompanied by pathologic manifestations 

 which constitute the anaphy lactic crisis. 



