TEXT-BOOK OF BACTERIOLOGY. 271 



Pettenkofer intelligently says that "the cholera germ (x) pro- 

 duces, on the ground of local and temporal disposition of the soil 

 (y), the cholera poison (z), just as the torula cerevisiae (x) produces 

 from the sugar solution (y) the poison of inebriating alcohol (z)." 



This cholera poison is transmitted to man by air and absorbed 

 exclusively by way of respiration. 



It is thus seen that the soil plays the principal part in this view. 

 The poison must every time be matured there, as it were, before it 

 can attack man, who really stands second, and must, moreover, be 

 especially susceptible to the invasion of the virus in consequence of 

 a certain individual predisposition. 



Now, when the comma bacillus appeared on the stage, they tried 

 first to insert it in the place of that x in the solid structure of 

 Pettenkofer's doctrine. And when it did not willingly comply with 

 this demand force was used, and it was declared to have forfeited 

 its right as the exciter of cholera. 



It was a completely forlorn undertaking. We should either (on 

 the ground of direct observations) refute the fact that the comma 

 bacillus is the cause of cholera and then remove, one bj' one, the 

 proofs for the view that the comma bacillus is met with in all cases 

 of cholera, that it goes side by side with the development of the 

 symptoms of this disease, and, on the other hand, only appears 

 with the cholera; or we should bow to the weight of these reasons 

 and recognize the significance of the bacillus. This being so, there 

 is but one proceeding. On the ground of the new discovery we 

 must subject to a new examination all the ideas and views formed 

 till now regarding the disease, as a whole or singly. If they find 

 their explication in the living properties in the special peculiarities 

 of the micro-organism, if they agree with or, at least, do not di- 

 rectly contradict them, their title is proved and they remain intact. 

 But if this should not be the case, they must be cheerfully shelved 

 with the calm acknowledgment that every fragment of our 

 knowledge retains its validity only so long as it is not replaced by 

 something better. But we must not proceed in the opposite direc- 

 tion ! We must not attempt, for the sake of a preconceived opinion 

 (however well founded it may seem to be), to trim facts that cannot 

 properly be twisted about or explained away, and, according to epi- 

 demiological observations, constitute an artificial micro-organism 

 with prescribed qualities. 



But Pettenkofer's view positively could not be reconciled with 

 the living qualities of the comma bacillus. 



Not a single fact' points to the existence of a special cholera 

 poison produced by the bacterium and absorbed by man, independ- 



