1885.] on Cholera: its Cause and Prevention. 299 



a given town or country remains exempt from cholera — is not that 

 the seed of infection fails to reach it, but that those local conditions 

 which are necessary for its vegetation are wanting. If we call the 

 environment y, then the cause of cholera is not x4-y, but xy, so that 

 whatever value we assign to x, the product disappears as y vanishes.* 



If the cholera organism multi])lies in the soil, not in the indivi- 

 dual, it must, in order to exercise its disease-jDroducing function, 

 attack the human body by one of two channels, either by air or food ; 

 it must be taken in either by breathing or swallowing, for the skin 

 has so little power of absorj^tion that it need not be considered. It 

 seems to be extremely probable that in either case x enters the 

 organism by the same portal — namely, by the process of intestinal 

 absorption ; that is, by the same channel by which the nutritious part 

 of our food is assimilated — i. e. that even if it were introduced by the 

 breath, it would still act by localising itself in the alimentary canal. 

 Consequently, if we want to engage in the search for it, there are 

 two places where we should exj^ect and seek to find it — namely, first, 

 in the soil ; and secondly, in the intestine of infected persons. 

 Hitherto attention has been exclusively given to the investigation 

 of the absorbing apparatus of the alimentary canal as the spot in 

 which X would be likely to be caught as it were flagrante delicto. 



In illustration of this, let me now refer to the eflforts which have 

 been made at various periods to carry out this inquiry. Without 

 going back to the attempts made by Dr. Snow in the epidemic of 

 1854, I will content myself wdth a rapid survey of what has been 

 done in more recent times, premising that there is no necessary 

 connection between the notion which I am now advocating — namely, 

 that the cholera x resides in the soil, and produces cholera by finding 

 its way into the intestine, and the belief that the intestinal contents of 

 persons suffering from cholera are directly pernicious and infecting. 



In 1870 a morphologist of great distinction (Professor Hallier) 

 published a remarkable series of observations, in which he endea- 

 voured to show, on purely morphological grounds, that the birth- 

 place (or rather the nursery) of cholera is the rice-plant — that a 

 parasite which grows on this plant, so essential to the populations of 

 the endemic area of Bengal, becomes in the course of successive 

 transformations the cholera fungus; that this fungus throws off 

 spores which are the immediate producers of cholera ; and that by 

 means of the endurance and extreme levity of these spores, they 

 serve as agents by which cholera is spread all over by the wind ; and 

 so on. Of Hallier it is sufiicient to say that, however distinguished he 

 might be as a botanist, he was a bad pathologist, and that his method 

 was fundamentally wrong, inasmuch as he proceeded throughout on 

 the assumption that the morphological characters of an organism 

 supposed to be infective may be taken as evidence of its infective 



* In desiguating the seed, germ, coutagium, or miteries morhi of cholera x, and 

 the soil or environment y, I follow Professor v. Pettenkofer. 



