414 CHOLERA. 



As regards the powers of resistance in ordinary conditions, 

 the following facts may be stated. In cholera stools kept at the 

 ordinary room temperature, the cholera organisms are rapidly 

 outgrown by putrefactive bacteria, but in some cases they have 

 been found alive even after two or three months. In most 

 experiments, however, attempts to cultivate them even after a 

 much shorter time have failed. The general conclusion may be 

 drawn from the work of various observers that the spirilla do not 

 multiply freely in ordinary sewage water, although they may 

 remain alive for a considerable period of time. In distilled 

 water they remain alive for several weeks at least, but do not 

 multiply, nor does any considerable growth take place without 

 the presence of a pretty large proportion of organic matter. On 

 moist linen, as Koch' showed, they can flourish very rapidly. 

 When the cholera organisms are grown along with other organ- 

 isms in fluids at a warm temperature, it is found that at first 

 they may multiply more rapidly than the others, but that after 

 a certain time they are outgrown by some of the organisms 

 present, gradually diminish in number, and ultimately disappear. 

 It must not, however, be inferred from such experiments that a 

 similar result will necessarily follow in nature, as any particular 

 saprophytic organism requires a special habitat — that is, certain 

 suitable conditions for its growth in competition with other 

 organisms. Though we can state generally that the conditions 

 favourable for the growth of the cholera spirillum are, a warm 

 temperature, moisture, a good supply of oxygen, and a consider- 

 able proportion of organic material, we do not know the exact 

 circumstances under which it can flourish for an indefinite period 

 of time as a saprophyte. The fact that the area in which cholera 

 is an endemic disease is so restricted tends to show that the 

 conditions for a prolonged growth of thfe spirillum outside the 

 body are not usually supplied. Yet, on the other hand, there 

 is no doubt that in ordinary conditions it can live a sufficient 

 time outside the body and multiply to a sufficient extent, to 

 explain all the facts known with regard to the persistence and 

 spread of cholera epidemics. 



Numerous experiments show that the cholera organisms are, 

 as a rule, rapidly killed by drying, usually in two or three minutes 

 when the drying has been thorough, and it is inferred from this 

 that they cannot be carried in the living condition for any great 



