ACTIOJSf OF LIGHT ON MICRO-OKGA.NISMS Ml 



them not only remained alive, but acquired a more or 

 less pronounced degree of immunity. 



Nocard^ objected to Arloing's conclusions as to the 

 greater susceptibility to light of the spores than the 

 bacilli of anthrax, by suggesting that during the expo- 

 sure of the spores they had developed into bacilli, and 

 that the light had acted on the latter, and not on the 

 spores, as maintained by Arloing. 



Straus,^ in order to bring experimental evidence 

 to support this assertion of Nocard's, inoculated an- 

 thrax spores into sterilised distilled water, whilst, as a 

 control, a series of inoculations was also made into 

 ■sterile bouillon ; both sets of tubes were exposed to nine 

 hours' insolation. The result of these comparative 

 ■experiments was that all the spores in the bouillon 

 were found to be dead, whilst those immersed in dis- 

 tilled water yielded growths when inoculated into 

 >sterile bouillon. Straus explains this difference by 

 observing that whereas in broth the spores were able 

 to germinate into bacilli in spite of the exposure to 

 light in the distilled water, which does not afford a 

 suitable medium for the germination of the spores, they 

 remained, therefore, in the condition of spores, and 

 were thus able to withstand the action of light. 



Arloing ^ soon after published another memoir, con- 

 troverting Straus's conclusions. In this paper he refers 

 to experiments in which he distributed anthrax spores 

 in broth contained in vessels placed in contact with ice 



^ Recueil de Medecine vetm^inaire, 1885. 



^ ' Gharbon de rHomine et des Animaux,' Societe de Biologie, 1886, 

 p. 473. 



^ ' Les Spores du Bacillus Anthracis sont r^ellement tii^es par la 

 Lumi^re Bolairej' Compt. rendus, 7 Mars, 1887, vol. civ. p. 701. See 

 also another paper published by Arloing in reply to Nocard : ' Influence de 

 la Lumifere blanche et de ses Rayons constituants sur le D^veloppement 

 ■et les Propridtes du Bacillus Anthracis,' Archives de Physiologie normale 

 et pathologique, 1886, vol. vii., No. 3, pp. 209-235. 



