Report on the Bacteriology of Water. 



285 



Two other facts are worth note in these analyses. (1) The large 

 number of water organisms which had persisted through the seven 

 to eight months, and (2) the total absence of rapidly liquefying 

 forms. 



It was already clearly proved then that the presence of the green 

 alga? and the diffuse daylight had not exterminated the anthrax, 

 although the numbers were extremely diminished, for on starting 

 the experiment our flask contained something like 1,000,000 per 

 1 c.c, and more. 



To place the matter still further beyond doubt, however, we placed 

 25 c.c. of the water at 56° C. for twenty-four hours, and obtained 

 X anthrax colony in a 3-drop plate, and several plates with no trace 

 of anthrax ; then we got a 3-drop plate, among several with negative 

 results, showing 5 anthrax colonies, and finally a 12-drop plate with 

 38 anthrax colonies. 



It was observed that in all these cultures the anthrax colonies 

 came on very slowly, and had there been any liquefying bacteria 

 present, it is practically certain that we should have missed the 

 anthrax altogether. 



The conclusion is inevitable that although the anthrax had not- 

 been eliminated from this flask, it had been enormously diminished 

 in quantity, and enfeebled as regards the powers of germination of 

 the spores. 



This conclusion was made a certainty by the following test : — On 

 November 7 a guinea-pig was inoculated intra-peritoneally with 

 2J c.c* of the water in the flask; at first we thought it had escaped, 

 but it died on November 17. Cultures from the heart's blood 

 proved that it had died of anthrax ; but it took ten days for the 

 feeble and few spores to do the work. 



The chief interest attaching to this series of experiments, however, 

 is the proof that insolation rapidly rids the water of the spores of an- 

 thrax. I shall show later on that this is not only a very definite 

 action, but one capable of being more directly and easily demon- 

 strated than has hitherto been suspected. f 



Experimental Observations on the Bacterial Flora of the Thames. 



As already pointed out (p. 244), I have devoted considerable at- 

 tention to the normal aquatic bacteria of the river water, isolating 

 each form for further culture as it turned up in the course of the 



* This large dose was given because we found so few spores, and these apparently 

 very much enfeebled. 



f See our First Report ('Roy. Soc. Proc.,' vol. 51, 1892), pp. 199 and 237, for 

 the literature dealing with the action of light on bacteria. See also pp. 303 and 

 310 of this Report. 



