Report on the Bacteriology of Water. 



257 



January 29) with 1, 3, and 9 drops each respectively, and examined 

 next day. The annexed example is selected. 



1-drop plate = 5 colonies = 125 per 1 c.c. No anthrax. 

 3 „ =67 „ = 558 

 9 260 „ = 720 



This seemed to show that the vegetative bacilli rapidly disappear from 

 the water, a result apparently in accordance with the experience of 

 several previous observers. 



A liquefying bacillus was common on the plates, however, and 

 prevented our keeping them long enough to determine whether 

 anthrax was really absent, or merely slower in development than the 

 rest of the organisms. 



A new set of plates were made from Flask A on January 30, i.e., 

 the flask having stood 48 hours at 20° 0. 



1-drop plate = 107 colonies = 2675 per 1 c.c, 



while plates with 3 and 9 drops respectively liquefied so rapidly 

 that we could make no determinations of the numbers. 



No anthrax colonies were found to develop in the time, and 

 similar results were obtained next day, the flask having then stood 

 72 hours 



The 1-drop plate = 320 colonies = 7900 per 1 c.c. 



On February 2, the flask having stood 110 hours, a further set of 

 plates were prepared, but the colonies developed were so numerous 

 that we could not estimate them. On some of the plates, however, 

 very small anthrax colonies appeared, and even in relatively large 

 numbers. On the whole, this preliminary examination convinced us 

 that such plates may fail to show anthrax colonies, because the 

 normal water bacteria present develop so rapidly, and in such 

 abundance, that the anthrax has no chance, especially if bad liquefy- 

 ing forms are present. They also showed us that the water forms 

 increase in numbers, day by day, as the water stands. 



As our further experiments show, the conclusion that the anthrax 

 died in these flashs is quite unwarranted ; its persistence was due to the 

 formation of spores ; but at the stage here reached that was a ques- 

 tion to be inquired into. 



Series B'. 



This series was also designed to see whether virulent normal anthrax 

 was capable of living as bacilli, and multiplying in the Thames water, 

 either untouched or rendered sterile by filtration through porcelain 

 or by heat, or if it passes over into spores in the water. In this 

 series we boiled the Thames water for two hours. 



