ACTION OF LIGHT ON MICRO-ORGANISMS 367 



rise to virulent cultures. When the anthrax blood was 

 thinly spread over a cover-glass, an insolation of six 

 and a half hours was sufficient to destroy its lethal pro- 

 perties, for when fragments of this glass were introduced 

 under the skin of a guinea-pig no symptoms of anthrax 

 made their appearance. Bits of the same glass, how- 

 ever, placed in bouillon gave rise to virulent cultures. 

 Thus, in neither instance were the bacilli actually de- 

 stroyed, but their pathogenic properties were extin- 

 guished, although capable of revivification. The fibres 

 of the paper served apparently to protect the bacilli 

 from the full effects of insolation, the cover-glass ex- 

 posures losing their virulence far more rapidly. 



In these experiments the greater sensitiveness of the 

 bacilli enclosed in bouillon to those present in blood is 

 again shown very distinctly. 



Experiments in Sunlight on Asporogene Anthrax in Moist 

 Surroundings 



Into each of a series of glass tubes one drop of an as- 

 porogene anthrax bouillon culture was introduced ; the 

 tubes were then sealed up, remaining full of air. Into 

 other small tubes about ^ c.c. of such bouillon culture 

 was introduced ; these tubes being completely filled with 

 the liquid contained no air, and the apertures were sealed 

 in the blowpipe flame. The maximum duration of life 

 of the bacilli in the moist condition insolated in the 

 presence of air was two and a half hours ; whilst the 

 bacilli preserved in a moist condition, but in the absence 

 of air, were still living after insolation for fifty hours. 



These results show very strikingly that the agency of 

 light is immensely increased when acting in combination 

 with air. The last cultures obtained were very virulent 

 when inoculated into guinea-pigs. 



