ACTION OF LIGHT ON MICRO-ORGANISMS 347 



forms of anthrax is apparent only, and not real, serve 

 to explain what was before a most anomalous pheno- 

 menon with regard to these two forms of anthrax, and 

 also exhibit a fresh factor in the mechanism attending- 

 the bactericidal action of light, viz., the alteration 

 which the culture fluid may itself undergo during inso- 

 lation in the presence of air. We should, however, at 

 once point out that this alteration of the culture medium 

 through insolation has not hitherto been confirmed by 

 many observers ; but to this point repeated reference 

 will be made hereafter. 



The bactericidal action of light was again attacked 

 by Gaillard,^ who under the direction of Arloing carried 

 out a number of experiments with different varieties 

 of micro-organisms, the Bacillus fluorescens^ Staphylo- 

 coccus pyogenes aureus^ Bacillus prodigiosics, Bacillus 

 anthracis^ Bacillus typhosus^ Penicillium glaucum, Oidium 

 albicans^ and the ' Eosahefe ' (pink yeast). No very 

 important fresh results are recorded, but it was found 

 that sunlight acted prejudicially on the production of 

 colours by the so-called pigment producing bacteria, 

 that the sun's rays appeared to favour the development 

 of several kinds of yeast ^ and moulds, and finally 

 that the action of light was increased by the presence 

 of air. 



The Italians now took up the subject, and we find a 

 paper by Pansini ^ in which he describes his experiments 

 on various organisms, B. prodigiosus^ B. violaceus, B. 

 pyocyaneus, B. anthracis, cholera bacillus, B. mim- 



^ De VInfluence de la Luniiere sur les Micro-organisrnes, Lyon, 1888. 

 See also a Paper by Uffelmann, Die hygieniscTie Bedeiitung des Sonnen- 

 lichtes, 1889. . 



- In this connection it is worthy of note that Downes and Blnnt found 

 that the organisms which survived insolation in tubes filled with pure 

 oxygen were torula-forms. 



^ ' Azione dellaLuce solare sui microrganismi,' Bivista d'Igiene, 1889. 



