434 SPIRILLUM CHOLERA ASIATICJE. 



present at first in considerable excess, and if the condi- 

 tions as regards nutrition, temperature, reaction, and 

 presence of oxygen, are especially favourable, gain tbe 

 upper hand in the first instance, and thus form those 

 pure cultivations which have been observed on the 

 clothes of cholera patients, on moist soil impregnated 

 with dejecta, and in the culture vessels prepared by 

 Schottelius' method ; but after two or three days a 

 complete alteration in the character of the cultivation 

 occurs in these cases; the comma bacilli die, and other 

 bacteria gradually occupy the whole of the nutrient 

 substrata. If the saprophytes are in excess in the first 

 instance, or if the sum total of the conditions of life are 

 not very favourable to the comma bacilli, the latter do 

 not multiply at all, but the saprophytic bacteria lead 

 rapidly to the death of the comma bacilli present, either 

 by using up the nutrient material, or by producing 

 poisonous products. According to Koch's experiments, 

 comma bacilli when added to sewage could no longer be 

 demonstrated after 24 hours; in the water in the Berlin 

 Canal they died at the latest after 6 to 7 days. In 

 impure water also they do not retain their vitality as a 

 rule for a longer time, except when they are introduced 

 in very large quantities. 



Length of life If the two hurtful influences above mentioned are 

 bLmi iTur a e absent the vitality of the comma bacilli may be of 

 cultivations. i on g duration. They can be kept alive for months in 

 fluid, or, at any rate, moist, pure cultivations ; in gela- 

 tine cultivations they have been found living after 3 to 

 5 months, in agar cultivations after about 6 months (in 

 one case mentioned byHueppe after almost 10 months). 

 It is evidently not impossible that an equally long pre- 

 servation of living comma bacilli may at times occur in 

 linen which is kept moist, on various parts of the soil, 

 or on some object which is protected from drying and 

 from the entrance of other bacteria. But under normal 

 conditions cases of this kind must be of extreme rarity, 

 for the comma bacilli are almost always destroyed either 

 by drying or by the presence of such a large quantity of 

 water that the substratum is overgrown by other bacteria. 



