270 "SPECIFIC TREATMENT" OF DISEASE 



of producing other "anti-bodies" which neutralize 

 injurious agents other than toxins; of these we 

 may mention the bacteriolysins that kill and dis- 

 solve bacteria which invade the system. The anti- 

 toxins only neutralize the toxins. The formation 

 of bacteriolysins occurs in a similar way to that of 

 the antitoxins and they are likewise specific in 

 character. As examples may be cited those con- 

 tained in the serum of persons who have been 

 rendered immune to cholera or typhoid fever where 

 the bacteriolysins destroy the bacteria of cholera 

 and typhoid respectively but exert no effect on 

 other microorganisms. 



The foregoing investigations and discoveries 

 were the outcome of research by many investi- 

 gators in laboratories in different parts of the 

 world. A clearer conception arose as to the nature 

 of acquired immunity and recovery in infective 

 disease, but the complex character of the pheno- 

 mena was also more appreciated. 



The next step in advance was along the lines 

 of drug treatment in diseases like sleeping sickness 

 which are due to the Protozoa, the lowest forms of 

 animal life. It had long been known to those who 

 used the microscope in the study of the minute 

 anatomy or histology of animals and plants that 

 the cells of which their tissues and organs were com- 

 posed showed a peculiar behaviour towards dyes 

 of various kinds. Whereas the cells or parts of cells 

 of one organ in an animal could be successfully 



