CAUSING ACUTE INFECTIONS. 85 



infected with 5 per cent, carbolic solution, and the 

 disinfection should be continued for some time after 

 recovery. 



The constitutional symptoms that accompany 

 cholera are due to the toxins formed by the spirilla in 

 the intestines. They are partly thrown out by the 

 organisms, that is, soluble toxins, and partly retained 

 in the body of the bacterial cells and set free only 

 after their death. It is possible to immunize animals Immunit y 

 against cholera by injecting small amounts of the 

 killed cultures or very small doses of the living organ- 

 isms. The blood-serum 1 of animals immunized in this 

 way contains substances that dissolve the spirilla 

 bacteriolysins, and substances that clump them; 

 agglutinins. The agglutinins are made use of in diag- 

 nosing cholera in the same way as in the diagnosis of 

 typhoid fever (see Widal reaction). Human beings 

 that have recovered from cholera are immune to the 

 disease, but they remain so for only a few months. 

 Efforts to protect human beings by injecting the killed 

 cultures have been made in India on a large scale, but 

 the results have been only partially successful. 



THE BACILLUS OF DIPHTHERIA. 



Diphtheria is an infectious disease caused by the 

 diphtheria bacillus, sometimes called the Klebs-Loffler 

 bacillus, after the two men who discovered it. The 

 word diphtheria is derived from a Greek word mean- 

 ing leather, because of the characteristic false mem- 



