Report on the Bacteriology of Water. 



205 



refrigerator or incubator from the day of infection with anthrax 

 (March 18, 1892) until March 25, 1892, from when they remained in 

 a dark room until April 9, 1892, after which they were exposed to 

 the diffused daylight in a room with a southern aspect. 



An inspection of Table VI at once shows that the anthrax in the 

 previously sterilised (porcelain and steam) Thames water survives 

 this exposure to diffused daylight, nor does the number of colonies 

 obtained on plate cultivation differ materially from that obtained 

 from the corresponding flasks maintained throughout in the dark. 



On the other hand, the degeneration of the anthrax in the unsterilised 

 Thames water is distinctly more rapid in these flasks exposed to day- 

 light than in those preserved in the dark. Thus, in the case of the 

 unflltered Thames water (daylight) the special method of examina- 

 tion revealed no anthrax from May 17, 1892, whilst in the same 

 water, kept both in the incubator and refrigerator, anthrax was dis- 

 covered by the same method on July 9, 1892. 



The following experiments were made to test the virulence of the 

 flasks which had been thus exposed to diffused daylight : — 



Animal Experiment No. 5. — On October 8, 1892, 1 c.c. of water 

 from the flask " 1 1, Thames water, unflltered, infected with anthrax 

 on March 18, 1892, and exposed to daylight since April 9, 1892," was 

 subcutaneously injected into a white mouse. The mouse did not 

 succumb, but is alive to the present time (November 11, 1892), or 32 

 days after the operation. 



This result was to be anticipated, seeing that the corresponding 

 flasks 3 I and 3 K, which had not been exposed to daylight, also 

 failed to kill mice (see Animal Experiments Nos. 1 and 2). 



Animal Experiment No. 3. — On October 7, 1892, 1 c.c. of water 

 from the flask "51, Thames water, paper-filtered, which had been 

 infected with anthrax on March 18, 1892, and exposed to daylight 

 since April 9, 1892," was subcutaneously injected into a white mouse. 

 The mouse did not die, but is still alive, 33 days after the operation. 



It will be remembered that a corresponding flask, 1 R, which had 

 not been exposed to daylight did kill a mouse (see Animal Experi- 

 ment No. 8), so that the virulence has in this case been reduced by 

 the exposure. 



Animal Experiment No. 4. — On October 7, 1892, 1 c.c. of water 

 from the flask "51, Thames water, porcelain-filtered, which had been 

 infected with anthrax on March 18, 1892, and exposed to daylight 

 since April 9, 1892," was subcutaneously injected into a white mouse. 

 The mouse died within 6 days 20J hours. The body exhibited exten- 

 sive oedema ; the spleen was only slightly enlarged, but was found to 

 contain anthrax bacilli both microscopically and by cultivation in 

 gelatine. 



Animal Experiment No. 10. — On October 15, 1892, 1 c.c. of water 



