VIIL] THE INFECTIVENESS OF CHOLERA. 159 



It must not however be supposed that I mean to ques- 

 tion the statements that cholera dejecta have produced in- 

 fection, or that water contaminated with cholera dejecta has 

 produced cholera. Such cases of infection are well estab- 

 lished. Dr. Snow has minutely described one such epidemic, 

 the noted Broad Street Pump epidemic, and this is only 

 one among many noticed in former and recent epidemics in 

 Europe. As soon as a certain impure water-supply was 

 stopped cholera cases ceased ; to such a water-supply a 

 river or a well cholera dejecta had probably had access. 

 This question of the importance of drinking-water as a 

 vehicle of contagion may I think be considered settled. But 

 what is not at all settled is the question whether cholera 

 dejecta when fresh have any power to produce infection, or 

 whether some stage or change has to be passed through by 

 them in order to become infective. At any rate sufficient 

 evidence has been brought forward to show that fresh cholera 

 dejecta have not produced cholera even when mixed with 

 water used for various domestic purposes including drinking. 

 And I presume it is this consideration which led Lieber- 

 meister in his recent article on cholera l to say that the 

 choleraic comma-bacilli must possess the power of forming 

 spores, since only thus can the theory be brought into har- 

 mony with the obvious fact that fresh cholera dejecta have 

 often proved harmless. But to this the answer is obvious, 

 viz., that since the comma-bacilli do not possess, as has 

 been shown on former pages, this power of forming spores, 

 and since they have in many cases of direct and natural ex- 

 periment on a large scale failed to produce infection, it 

 follows that they cannot be the true cholera germ. A 

 similar criticism is applicable to all that is said by Koch 

 and the contagionists with regard to the infective power 

 1 Speciette Pathologic et Therapie, i. p. 83. 



