1885.] on Cholera : its Cause and Prevention. 295 



spreads of cholera over the civilised world it follows certain general 

 laws — as, for example, that it loves great rivers, and particularly their 

 deltas and estuaries, and that it is capable of being conveyed over 

 sea and land, following for the most 2)art the lines of commercial in- 

 tercourse. On either side of this general view which the unbiassed 

 intelligent reader of cholera history finds himself compelled to take, 

 range the opjDosite oj)inions of contagionists on the one hand, who 

 believe that cholera came to Europe in 1830, because the materies 

 morhi accidentally escaped from India ; and on the other, the believers 

 in the siDontaueous origin of cholera, who think that they mean some- 

 thing when they say that the cause of cholera is " atmospheric " or 

 " telluric." 



Let us now see what can be learned by looking at the subject 

 from the consideration of its pathological nature. With this view 

 we will take as our starting-point the assumption that cholera is a 

 " specific " disease, which means simply that it has a particular or 

 proper cause — a cause which is peculiar to it, and without which it 

 cannot come into existence. In each of the diseases known as 

 smallpox, glanders, diphtheria, cattle plague, the cause presents itself 

 as a tangible material which can be obtained from the body of any 

 human being or animal afi'ected with it, and may thus be subjected 

 to experimental investigation. In the case of the affection called 

 woolsorters' disease, or splenic fever, to which persons engaged in 

 manipulating particular kinds of wool imported from the East are 

 liable, we know that the material cause not only exists in the body of 

 the sufferer, but also in the wool by which he is infected. Cholera 

 we believe to have a similar material and tangible cause, but no 

 one as yet has been able to seize upon it. It has been sought for 

 both diligently and skilfully, but it has hitherto eluded investigation. 

 It will therefore be convenient to speak of it as the unknown entity x. 



In the search after the x of cholera which now occupies so many 

 minds, the method which the pathologist ought to follow — the only 

 one he can follow with reasonable prospect of success — is that of 

 proceeding step by step from the known to the unknown. Conjecture 

 must lead the way to discovery, but those conjectures only are likely 

 to be productive which are founded on the comparison of unknown 

 with known relations. 



The fact which we have to explain is that cholera has spread 

 from India all over the world, and is always spreading somewhere. 

 The knowledge we have to guide us in seeking for an explanation 

 is that in other spreading diseases the spread consists in the convey- 

 ance of a something tangible from the infected person or thing to 

 a healthy person at a greater or less distance; and the legitimate 

 guiding conjecture is, that whatever may be known as to the nature 

 of the conveyable something in the cases in which it can be investi- 

 gated, is likely also to be true in those cases in which, as in cholera, 

 it is for the present beyond our reach. 



In the current language of pathology, the conveyable something 



