178 A MANUAL OF BACTERIOLOGY 



agglutinins, bacteriolysins and antitoxins : to these the 

 general name of " anti-bodies " is given, and these may 

 now be considered. 



Anti-Bodies l 



Anti-bodies may and do develop as the result of a 

 natural infection, but much larger amounts are obtained 

 by the injection into an animal of complex substances, 

 such as bacterial toxins, bacteria, blood-corpuscles, cells 

 and cellular proteins, ferments, etc. Thus an animal 

 injected with sub -lethal doses of a bacterial toxin, 

 e.g. diphtheria toxin, acquires a tolerance towards the 

 toxin, becomes immunised, and a substance is developed 

 in the blood that antagonises the toxin which was injected ; 

 this substance is known as antitoxin. If bacteria be 

 injected, the fresh blood-serum in vitro acquires a solvent 

 action on the bacteria (bacteriolysis), and also an agglu- 

 tinating action upon the bacteria employed ; if blood- 

 corpuscles be injected, the fresh blood-serum becomes 

 solvent for the same kind of blood-corpuscles (haemolysis) ; 

 if cells be injected, the blood-serum has a solvent action 

 on the cells (cytolysis), and so on. If ferments be injected, 

 anti-ferments are formed and will prevent the specific 

 action of the ferment. Antitoxins, bacteriolysins, agglu- 

 tinins, etc., are also formed in the course of a natural 

 infection, but not nearly to the extent that they may be 

 after artificial inoculation. Traces of them are also present 

 normally in the uninfected and the untreated animal. With 

 doubtful exceptions, 2 it is only complex bodies of pro- 

 tein nature, or allied to the proteins, which give rise to 

 the production of anti-bodies on inoculation ; alkaloids, 



1 All the subjects dealt with in the subsequent portion of this chapter 

 are discussed in detail in Kolmer's Infection, Immunity and Specific Therapy 

 (W. B. Sanders Co., 2nd ed., 1917). 



2 Ford has described the formation of an anti-body by the injection of a 

 poisonous glucoside derived from fungi. 



