Report on the Bacteriology of Water. 



175 



which admits of the most ready determination, and it is quite 

 unaccountable why in the experiments made on the Continent 

 it should have been so frequently neglected. 



Object and Nature of our Experiments. 



One of our first objects has been to make ourselves acquainted with 

 the nature of the waters, and especially that of the Thames, selected 

 for investigation ; and this not only as regards their chemical com- 

 position, but also as regards the nature and numbers of organisms 

 normally found in the water. We have also made inquiries as to the 

 changes the water undergoes on standing, and have acquired much 

 interesting information regarding these points. 



In pursuing the inquiry as to the vitality of anthrax in water, we 

 have been guided by the following considerations. As already 

 pointed out, we selected the Bacillus antlnracis for the first series of 

 our investigations on the vitality of pathogenic bacteria in water, 

 because it constitutes almost the extreme term, so to speak, in the 

 series of pathogenic organisms which are at present known. In the 

 form of spores it presents one of the hardiest and most refractory 

 examples of living organisms, # at any rate of the pathogenic kind, 

 for amongst the non-pathogenic forms there are a number which 

 excel it in this respect ; whereas our information as regards the 

 bacilli in water is most incomplete, though the whole practical in- 

 terest as regards pathogenic organisms turns on their behaviour in 

 the vegetative — spore-free — condition, and on whether they can 

 multiply or develop spores in the water. 



In introducing the anthrax bacilli and their spores into British 

 waters of typical character, we have endeavoured to ascertain whether 

 their fate is affected (a) by differences of temperature such as occur 

 in the natural course of events, (6) by the other bacteria present in 

 the water ; and, in orde^ to ascertain this point, we have employed the 

 waters in question in their natural state, unsterilised ; also sterilised 

 by heat (steam) in the ordinary way; and, thirdly, sterilised without 

 the application of heat by filtration through unglazed porcelain. 



We have also endeavoured to ascertain whether the sporiferous 

 anthrax bacilli are differently affected according as the water in 

 which they are resident is kept in darkness, placed in diffused light, 

 or exposed to direct sunshine. 



* Pasteur showed (' Compt. Eend.,' 1877, vol. 85, p. 99) that they remain alive for 

 some time in absolute alcohol, and for twenty-one days exposed to a pressure of 

 10 atmos. of pure oxygen. Koch has shown (' Mitth. a. d. Kaiserl. G-es. Amt.,' I, 

 p. 32) what extreme temperatures they will endure, and Klein declares that 

 ten minutes' boiling cannot be relied on. We have already given the literature 

 showing that the spores remain for long periods alive in water, and it is well 

 known they can be kept intact for months on silk threads in the dark. 



