584 BACTERIOLOGY. 



become completely dry there is little danger. Farther, 

 we must conclude from the distribution of the cholera 

 bacillus in the body and from experiments upon ani- 

 mals that the commonest mode of infection is by way 

 of the mouth, and chiefly by means of water used for 

 drinking purposes, for the preparation of food, etc. In 

 recent times cholera spirilla have been found not infre- 

 quently in water (wells, water-mains, rivers, harbors, 

 and canals) which have become contaminated by the 

 dejections of cholera patients. 



But, like other infectious diseases, not everyone who 

 is exposed to infection is attacked by cholera. The 

 bacilli have been found during cholera epidemics in the 

 dejections of healthy individuals without any patholog- 

 ical symptoms. Abel and Claussen found, for example, 

 in 14 out of 17 persons belonging to the families of 7 

 cholera patients, cholera vibrios, in some of them for a 

 period of fourteen days. In Hamburg there were 28 

 such cases of healthy choleraic individuals with abso- 

 lutely normal stools. It is evident, therefore, that an 

 individual susceptibility is requisite to produce the dis- 

 ease. In the normal healthy stomach the hydrochloric 

 acid of the gastric secretions may destroy the spirilla; 

 and, finally, the normal vital resistance of the tissue 

 cells to the action of the cholera poison may be taken 

 into consideration. According to the greater or less 

 power of this vital resistance of the body the same 

 infectious matter may give rise to no disturbance what- 

 ever, a slight diarrhoea, or it may lead to serious results. 

 Furthermore, it may be accepted as an established fact, 

 that recovery from one attack of cholera produces per- 

 sonal immunity to a second attack for a considerable 

 length of time. This does not appear to depend upon 



