368 MICRO-ORGANISMS IN WATER 



Momont concludes his most interesting memoir with 

 an account of the behaviour of anthrax spores in sun- 

 light. 



Antheax SFO'RE.s.^Action of Light on 



Dried spores insolated in the presence of air for more 

 than 100 hours yielded broth cultures, the development 

 of which was delayed for from one to four days. These 

 cultures were very virulent. Dried spores obtained 

 from the same source and insolated for 100 hours in 

 vacuo after being inoculated into bouillon yielded very 

 virulent cultures. 



Thus dried spores resist the action of sunlight for 

 a long time, whether in the presence or absence of air. 

 We shall describe later on Moment's experiments on 

 the behaviour of anthrax spores when insolated in water 

 (seep. 371). 



These extremely interesting and suggestive investi- 

 gations were conducted by Momont in M. Eoux's 

 laboratory in the Institut Pasteur. It will be remem- 

 bered that it was Eoux who first demonstrated con- 

 clusively the changes in the culture medium which 

 may be induced during insolation ; to eliminate this 

 difiiculty and render the problem less complicated, and 

 ascertain, if possible, the exact effect produced by 

 insolation on the anthrax bacteria themselves, Momont 

 has invariably tested the vitality of the insolated speci- 

 mens by subsequently introducing them into fresh 

 bouillon preserved from light. If they were found in- 

 capable of revivification by this means, then, and only 

 then, was it assumed that they were destroyed. The 

 mere fact that during insolation the bouillon remains 

 clear is not a guarantee that the contained anthrax 

 organisms are killed, as has been assumed by many 

 observers ; it may only mean that the culture me- 



