CHAPTER VII 



THE PRODUCTION OF ACTIVE IMMUNITY 



WITH THE SPLIT PRODUCTS OF THE 



COLON BACILLUS 1 



IT may be stated that the work which we have done 

 with the colon bacillus up to the present time has in every 

 instance upheld the belief that the substances which give 

 rise to the phenomena occurring in animals infected with 

 the living colon germ exist as essential groups within 

 the bacterial cell and can be liberated from the latter 

 only by its disruption. Moreover, until these substances 

 have been separated from the other constituents of the 

 bacterial cell with which they are normally combined they 

 are unable to exert any deleterious action upon the body 

 cells. If the belief that the phenomena which result from 

 infection with the colon bacillus are due to the action of 

 the intracellular constituents of this organism is correct, 

 we would expect that it might be possible by chemical 

 means to split up this bacillus into different groups, the 

 injection of some of which into animals would be followed 

 by some of the results which are seen after inoculation with 

 the living germ. In a previous chapter we have shown that 

 it is possible to split off a toxic group which causes death 

 in animals with symptoms similar to those observed after 

 the injection of a fatal dose of living bacilli. However, 

 death is by no means the sole phenomenon which results 

 from the inoculation of animals with the colon bacillus. 

 The results which follow the injection of non-fatal doses of 

 the living germ are of equal if not of greater importance. 



1 This chapter is taken, with but few changes, from an article by Victor 

 C. Vaughan, Jr., in the Journal of Medical Research, 1905, xiv, 67. 



