PRACTICAL APPLICATIONS 409 



the neutralization of the toxin or its destruction or elimination 

 constitutes the whole process of cure. There is a little evidence 

 in favour of the formation of bacteriolytic substances, though 

 experimental evidence on this point is not unanimous. Bandi, it 

 is true, claimed to have been able to immunize animals to the 

 bacilli themselves, and prepared a serum which was supposed to 

 have bactericidal properties ; it has been prepared by others, and 

 can be obtained commercially. It is supposed to be used locally, 

 either in the form of a powder or of lozenges, and is intended to 

 supplement the action of antitoxin. Rist, however, failed to 

 immunize animals to the bodies of the bacilli, and though Lipstein 

 was more successful, his serum was apparently inert as a protective 

 agent. It contained, however, an agglutinin, and the interesting 

 fact was noticed that it only clumps bacilli of the culture used 

 for the injection. This is of some interest, since the Klebs-Loffler 

 bacillus has always been looked upon as a very definite bacterial 

 species; the toxins it produces are always neutralized by the 

 same antitoxin, and though they may be produced in larger or 

 smaller amounts and may contain varying proportions of proto- 

 toxoids, etc. (on Ehrlich's theory), appear to be the same substance 

 in all cases. These experiments would tend to show that, though 

 the bacilli of various types agree in their metabolic products, they 

 may differ in the constitution of their protoplasm. 



The observations referred to previously, show clearly that the 

 process of cure of the local lesion is assisted by the produc- 

 tion of an opsonin. And there is every reason to believe that 

 it is by phagocytosis that the bacilli are combated, bacteriolysis 

 being very doubtful and of comparatively small importance. 

 The cure of the disease therefore is accomplished partly by one 

 or more of the methods discussed in Chapter VI., and partly 

 by phagocytosis. 



Diagnosis. This is made by the demonstration of the bacillus. 

 If necessary, the opsonic test might be used, and Bordet and 

 Gengou have shown by their method of fixation of complement 

 that " sensibilatrices " circulate in the blood. These methods are 

 quite unnecessary. The absolute recognition of diphtheria 

 bacillus in cultures can best be made by an application of an 

 immunity reaction. A pure culture in broth is divided into two 

 parts, and each injected into a guinea-pig. One of the animals 

 receives a large dose of antitoxin, and should this remain unaffected 

 whilst the other dies, the culture is certainly diphtheria. The 



