272 TEXT-BOOK OF BACTERIOLOGY. 



ent of it, as the real cause of the disease. This cholera poison is 

 identical ivith the micro-organism itself. 



It is neither directly proven nor very probable that the micro- 

 organism is to prosper in the soil and to find in it the most import- 

 ant seat of its activity. The possibility may be admitted; for we 

 have seen that the comma bacillus is able to exist outside of the 

 human body and to lead a saprophytic mode of life. But the soil 

 itself is scarcely a fit place for it. The ample quantities of bac- 

 teria of other kinds dwelling- in the upper strata of the earth will 

 make life difficult to the delicate cholera vibrio so little capable of 

 resisting such a rivalry. 



The cholera poison (hence the comma bacillus) is, besides, said to 

 rise from the soil to be absorbed by respiration. Now, we know 

 that the bacteria are unable to fly upward independently or to pass 

 from a moist basis into the atmosphere by currents of evaporation. 

 There is but one way in which micro-organisms can be torn and 

 carried off from their culture medium, viz., by the desiccation and 

 subsequent scattering like dust. But the comma bacilli are exceed- 

 ingly sensitive to desiccation and rapidly perish under its influence. 

 We know, as yet, no persisting form of the cholera bacteria, and 

 as long as such a one has not been ascertained, this kind of trans- 

 mission is almost unimaginable. 



The entrance of the cholera poison through the lungs is, in con- 

 clusion, not supported by any fact. Aside from the intestines, the 

 bacteria appear neither in the blood nor in other organs. The dis- 

 ease points altogether to the fact that the intestine stands in the 

 centre of the pathological processes and that there the principal 

 changes take place. 



It is thus evident that the comma bacillus is not in accord with 

 Pettenkofer's views. Koch has, therefore, most decidedly opposed 

 the latter in almost every essential point by trying to explain the 

 origin of the disease by the qualities of its cause. 



Cholera is transmissible from man to man. This does not, as 

 a rule, occur directly, but as follows: 



The comma bacillus enters the intestine, develops and increases 

 there, and produces the severe symptoms composing the clinical 

 picture of the disease. It is received in the body by way of diges- 

 tion, with the food, frequently with the drinking-water, and leaves 

 it only with the discharges. It then spreads, gets again into the 

 water, or on moist food, wet linen, etc., and by means of these 

 agents finds occasion to attack other previously healthy individuals 

 who are susceptible owing to a certain predisposition, especially 

 a weakness of the intestinal canal. 



