32 2 PA THOGENIC BA CTERIA. 



matic. Pettenkoffer's theory is that the disease has 

 much to do with the ground-water and its drying zone. 

 He regards as the principal cause of the disease the de- 

 velopment of germs in the subsoil moisture during the 

 warm months, and their impregnation of the atmosphere 

 as a miasm to be inhaled, instead of ingested with food 

 and drink. This idea of Pettenkoffer's, combined with 

 his other idea that individual predisposition must pre- 

 cede the inception of the disease, is scarcely compatible 

 with what has gone before, and cannot possibly be made 

 to explain the march of the disease from place to place 

 with caravans, or its distribution over extended areas 

 when fairs and religious gatherings among the Hindoos 

 break up, the people from an infected centre carrying 

 cholera with them to their homes. 



While it is an organism that multiplies with great 

 rapidity under proper conditions, the cholera spirillum 

 is not possessed of much resisting power. Sternberg 

 found that it was killed by exposure to a temperature 

 of 52 C. for four minutes. Kitasato, however, found 

 that ten or fifteen minutes' exposure to a temperature 

 f 55 C. was not always fatal. In the moist con- 

 dition the organism may retain its vitality for months, 

 but it is very quickly destroyed by desiccation, as was 

 found by Koch, who observed that when dried in a thin 

 film its power to grow was destroyed in a few hours. 

 Kitasato found that upon silk threads the vitality might 

 be retained longer. Abel and Claussen have shown that 

 it does not live longer than twenty to thirty days in fecal 

 matter, and often disappears in one to three days. The 

 organism is very susceptible to the influence of carbolic 

 acid, bichlorid of mercury, and other germicides. 



The organism is also destroyed by acids. Hashimoto 

 found that it could not live longer than fifteen minutes 

 in vinegar containing 2.2-3.2 per cent, of acetic acid. 



This low vital resistance of the microbe is very fortu- 

 nate, for it enables us to establish safeguards for the pre- 

 vention of the spread of the disease. Excreta, soiled 



