262 TEXT-BOOK OP BACTERIOLOGY. 



retain the power of development tor months in moist surroundings, 

 thej' perish in a dry condition frequently within a few hours. 



It is true, facts have been observed in rare cases, which apparently 

 contradict this assertion. Kitasato and Berckholtz, for instance, 

 have independently established the fact that cholera bacteria at- 

 tached to silii threads (especially when moisture had been with- 

 drawn from them in the desiccator) remained alive for weeks and 

 even months. But these are decided exceptions due to the manner 

 of drying, the thickness of the culture medium, etc., and the fact 

 first perceived by Koch and his companions in India, that in drying' 

 the comma bacilli die more quickly than most other micro-organ- 

 isms, is generally maintained. 



As to the ability of the comma bacilli to resist the presence of 

 other bacteria and of struggling for existence in rivalry with them, 

 Koch had ascertained that they are overpowered and quickly dis- 

 appear in putrescent liquids. Kitasato and Uffelmann saw them 

 perish within a few days in artificial mixtures of faeces; but Gruber 

 and others observed them in putrescent evacuations of the bow^els 

 and separated them therefrom in pure culture. Here, too, special 

 conditions are important, such as the influence of temperature, the 

 kind of bacteria happening to come in contact with the comma 

 bacilli, the concentration of the media, etc. We must, therefore, 

 beware of establishing absolutely valid laws concerning the capac- 

 ity of endurance of the cholera bacilli, and only declare in a general 

 way that they are exceedingly delicate structures and quickly suc- 

 cumb, as a rule, to external influences. 



The comma bacilli principally require in our artificial cultures 

 the unobstructed access of atmospheric air. This requirement is 

 modified only under certain circumstances. If they are, for instance, 

 grown according to Hueppe in raw eggs, they will flourish in spite 

 of the supply of oxj^gen. In the intestinal canal of man they are 

 likewise shut off from a supply of oxygen. It is possible that they 

 may obtain some oxygen in these locations hy splitting up mole- 

 cules containing this gas by a reduction process. 



The comma bacillus develops equally well at a room-temperature 

 as at the temperature of the incubator; in the latter, however, it 

 grows much more rapidly and luxuriantly. It fails above 42° C. 

 and below 15° C. 



The cholera bacillus is stained by the various anilin colors ; but 

 a saturated watery solution of fuchsin is the most eflBcient. But 

 it must be observed that the coloring matter is frequently absorbed 

 with some difficulty, so that cover-glasses must be treated with the 

 stain for at least ten minutes, and even be heated in it in order to 



