22 THEORIES OF IMMUNITY 



future excitations with less danger and fatigue. But it often 

 happens that the cell in this process of defense and rehabili- 

 tation exceeds the normal reaction: it makes a "normal 

 antibody" in much larger quantity than it can use and then 

 expels the excess, which passes into the blood and the fluids 

 to become antibody in excess or antitoxin, which is found in the 

 serum of a hyperimmunized animal and which may be used 

 to cure disease in another subject, provided this disease is 

 caused by the same toxin secreted by the same germ. 



Antibody-in-excess is then a substance which, according 

 to its definition, does not need to be transformed in order to 

 be assimilated. It is "homologous" for the organism and 

 may be considered as a sort of "substance in reserve" which 

 the organism may resorb according to its need. 



Such as it was formulated by Ehrlich the theory of immun- 

 ity based on the general principles of chemical affinities is 

 applicable in reality to only a small number of special dis- 

 eases caused exclusively by certain toxins as diphtheria and 

 tetanus and even in these cases Ehrlich was obliged to add 

 purely hypothetical distinctions between certain properties 

 "toxophores" and " haptophores" of each toxin to explain 

 and distinguish their pathogenic and their immunizing 

 action. 



As to the mechanism by which a pathologic state could 

 be provoked in an organism by infection; as to the question 

 of knowing why different diseases differed from each other 

 by a special evolution and by a total of symptoms more or 

 less characteristic to each; why in certain cases the processes 

 of immunization are complicated by an inverse process known 

 since the time of Charles Richet as " anaphylaxis" ; and 

 finally, why there are certain substances for which the organ- 

 ism makes specific "antibodies" and others for which it does 

 not make them, as well as other questions, neither the one 

 nor the other of the two theories can explain. 



Should we conclude that these theories cannot be of any 

 use because they are almost always incomplete and inade- 

 quate? Certainly not! 



General ideas are always necessary to stimulate the studies 

 of new generations along new lines. 



