380 MICRO-ORGANISMS IN WATER 



Vitality and Virulence of Sporiferous Anthrax in Thames 

 Water Exposed to Direct Sunshine (Percy Frankland) 



The flasks infected with sporiferous anthrax bacilli 

 on March 18 were taken from, the incubator and 

 refrigerator respectively on March 25, 1892 ; they re- 

 mained in a dark room from that day to April 9, 1892, 

 and from then onwards they were exposed to as much 

 sunshine as could be conveniently obtained, and which 

 was approximately estimated in hours, although it is- 

 obviously very difficult to make any exact determina- 

 tion of the latter. The temperature of the water so 

 exposed never exceeded 32 C. 



The results, which are very striking, are easily fol- 

 lowed, thus : 



Unaltered Thames water , anthrax was still alive on 

 May 2, 1892, after 56 hours' sunshine, but extinct on 

 May 12, 1892, after about 84 hours' insolation. 



Paper-filtered Thames water, anthrax was almost 

 extinct on May 15, 1892, after about 92 hours' insola- 

 tion, and quite extinct on June 17, 1892, after about 

 151 hours' sunshine. 



Thames water filtered through porcelain, anthrax was 

 still alive on May 2, 1892, after about 56 hours of sun,, 

 but extinct on May 12, 1892, after about 84 hours' 

 insolation. 



Thames water sterilised with steam, anthrax was still 

 alive on May 2, 1892, after about 56 hours', but dead 

 on May 12, 1892, after about 84 hours' sunshine. 



In consequence of the sunshine having destroyed 

 the greater number of those water bacteria causing 

 liquefaction of the gelatine, it was possible to incubate 

 the plates for a long period of time, and thus in most 

 instances to dispense with the special method of ex- 

 amination by preliminary heating. 



