BACILLUS DYSENTERIC 129 



Animals do not contract cholera either spontaneously 

 or artificially, but they may be killed by the germs or 

 their poisons. The active acquired immunity they get 

 by repeated injections has been described. It has not 

 been found practical to obtain any serum from animals 

 which can be injected into human beings as a treat- 

 ment. Dead spirilla, however, can be injected into 

 well persons as a protective measure, precisely as is 

 done for typhoid and plague, and with good results. 



FIG. 37 



Spirillum of Asiatic cholera: /, stained by ordinary method; //, stained 

 to show flagella. (Abbott.) 



BACILLUS DYSENTERIC 



Dysentery occurs in two forms the bacillary type 



and the amebic type. The former is caused by bacteria, 



while the latter is a protozoon disease (see Chapter 



XIV). Bacillary dysentery is an acute infectious 



9 



