1885.] on Cholera : its Cause and Prevention. 297 



pended in the air. If it is not so, it remains to be determined 

 whether such events as the conveyance of cholera from Ceylon to 

 Mauritius in 1819, from Astrachan up the Volga in 1830, from 

 Hamburg to Sunderland in 1831, frorh Dublin to Montreal in 1832, 

 and from Havre to Halifax in 1849, in all of which immigration 

 from infected places of men with their belongings led to the appear- 

 ance of cholera where it was before unknown, should be attributed 

 exclusively to the introduction into these places of persons actually 

 suffering from cholera, or to the circumstance that these persons, 

 whether themselves infected or not, brought with them an infected 

 environment. Experience all over the world is in favour of the 

 latter alternative, for on the one hand it teaches that cholera is not 

 " catching," so that attending on the sick is in itself unattended 

 with any risk ; and, on the other hand, that cholera has such a 

 power of haunting localities, that a house, street, town, or district 

 where cholera prevails to-day becomes thereby more liable to a 

 second visitation next year than it would otherwise be. Now the 

 only way in which such a fact as this can be explained is by sup- 

 posing that the material cause of cholera is capable of existing in 

 human belongings for a length of time independently of the human 

 body from which it sprang. But in addition it suggests something 

 as to the nature of that cause. That the contagium of cholera is 

 capable, after many months of quiescence, of recovering its activity 

 whenever the conditions of that activity come into existence, is a 

 fact which, while it is otherwise unintelligible, is very easy explained 

 on the supposition that the contagium itself is endowed wdth life ; 

 for it is characteristic of living things that they have the power 

 of sleeping and waking — of hibernating, and reviving under the 

 influence of summer warmth. In addition to this, we are led in the 

 same direction by the consideration, which applies to cholera in 

 common with all other spreading diseases, that whatever the x may 

 be, it certainly possesses another essential property of organisms— 

 namely, that it is capable of self-multij)lication ; for however incon- 

 sideralDle may be the weight of material which is wanted for the infec- 

 tion of a single individual, it is clear that when cholera invades a 

 country for the first time, the increase of that material, in the body 

 of the first case, then in the bodies of the thousands subsequently 

 affected, must be enormous. 



The conjecture therefore that cholera, like other epidemic diseases, 

 owes its power of spreading to a living and self-multiplying organ- 

 ism is so well founded that we are justified in taking it as a starting- 

 point from which we may at once proceed to inquire — first, where 

 this self-multiplication takes place ; and secondly, how it is brought 

 about. The first question, I think, I can best answer by stating 

 to you the view on the subject which has received the most general 

 acceptance. 



In splenic fever, as we have seen, there is no doubt whatever that 

 the disease of which the human being or the animal affected with it 



