Report on the Bacteriology of Water. 555 



Thus at the temperature of 19 C., the behaviour of the anthrax bacilli 

 in these same waters was entirely different ; far from their undergoing 

 rapid diminution in numbers followed by early disappearance, they only 

 exhibited slight diminution during the first few days after their introduc- 

 tion, upon which there folloived an enormous multiplication. This 

 multiplication was already observable, in the case of one tube, on the 

 second day after infection, whilst on the fifth day it was very pronounced 

 in all the tubes, and on the fourteenth day the numbers reached were very 

 large, remaining practically unaltered even on the forty-second day. 



The explanation which naturally suggests itself for this entirely 

 different behaviour of the anthrax bacilli at the higher and the lower 

 temperature respectively, is that at the higher temperature of 19 C. 

 the anthrax bacilli can form spores, whilst at the lower temperatures 

 this sporulation cannot take place. With the appearance of the 

 spores, however, the longevity of anthrax in sterile potable water 

 becomes, as was shown in the Second Report, practically indefinite. 



In order to test the validity of this hypothesis that sporulation had 

 taken place in the waters kept at 19 C., the following experiments 

 were made : 



(1.) 1 c.c. of the contents of Tube 11 (Thames water, see table 

 above) was kept at 70 C. for ten minutes, in order to 

 destroy anthrax bacilli ; on subsequent plate cultivation, 

 innumerable anthrax colonies were obtained. 



(2.) A similar experiment made with 1 c.c. of the contents of 

 Tube 12 (Thames water, see table above) gave exactly the 

 same result. 



(3.) A similar experiment made with 1 c.c. of the contents of 

 Tube 5 (Dundee water, see table above) gave the same 

 result, innumerable anthrax colonies being obtained on the 

 plate. 



(4.) A similar experiment made with 1 c.c. of the contents of 

 Tube 6 (Dundee water, see table above) gave 23,352 anthrax 

 colonies. 



Thus in the case of all these waters kept at 19 C., it is evident 

 that practically the whole of the anthrax microbes present at the end 

 of forty-two days were there in the condition of spores, showing as 

 they did no appreciable 'diminution in numbers by the process of 

 heating to 70 C. for ten minutes. 



These experiments show, then, very clearly that the fate of virulent 

 anthrax bacilli passing from an anthrax victim into potable water 

 will be dependent on the temperature of the latter ; if the tempera- 

 ture of the water is below that at which sporulation of anthrax can 

 take place, then the bacilli will perish in the course of a few days ; 

 whilst if the temperature is high enough to admit of sporulation, 



