ON THE INFLUENCE OF INSOLATION UPON CULTURE MEDIA AND OF DESICCATION 

 UPON THE VITALITY OF THE BACILLUS OF TYPHOID, OF THE COLON BACILLUS, 

 AND OF THE STAPHYLOCOCCUS PYOGENES AUREUS.' 



By Dr. J. S. Billings, U. S. A. 



At the meeting of the National Academy in Washington in April, 1804, I j)reseuted a paper 

 upon the influence of light upon the bacillus of typhoid and the colon bacillus, giving the results 

 of experiments made at the Laboratory of Hygiene of the ITiiiversity of Pennsylvania by Dr. 

 Adelaide W. Peckham, in accordance with a general scheme of investigation piepartpd for that 

 purpose by Dr. Weir Mitchell and myself. 



This paper has not yet been ])ublished, and within the last three months there has api)eared 

 in the thud Heft of the uiuth volume of the Arheiten aiis dem Kuiserlichen Gcsuudlicitsdmtc a 

 paper by Dr. A. Dieudonne, entitled " Beitrage sur BeurtheUung der Einwirli^uuj des Lichtes auf 

 Buliterienj' in which he gives, as the results of experiments ou the effects of sunlight on bacteria 

 by methods which are almost identical with those used by Dr. Peckham, results which are 

 substantially the same as those announced in my iiaper above referred to. 



I desire now to present to the Academy certain results which have been obtained since last 

 April iu experiments upon the influence upon certain microorganisms of culture media which 

 have been exposed to sunlight, and of desiccation of the bacteria themselves. These experiments, 

 like those previously reported, were made in the Laboratory of Hygiene of the LTmversity of 

 Pennsylvania by Dr. Adelaide W. Peckham, in accordance with the general scheme iirepared by 

 Dr. Mitchell and myself, the expenses of the investigation having been borne by an appropriation 

 from the Bache fund. 



I. RESULTS OF INSOLATION OF CULTURE MEDIA. 



Sterile bouillon msolated from one to ten days and then inoculatvd with the hdciUii.s typhi 

 abdomimdls showed no diminution iu the number of colonies as compared with a control plate. 

 Twenty days' insolation and then inoculation with the typhoid bacillus showed great decrease in 

 the number of colonies ou all the ])lates; some of them were perfectly sterile. Insolation of forty 

 days and inoculation in the same manner gave very few colonies for each plate, probably the 

 same as the number of germs introduced, i. e., there had been no development. Bouillon iusolated 

 fifty to sixty days and inoculated gave perfectly sterile tubes. This iusolated bouillon, after 

 inoculation and incubation, remained perfectly clear, and plates made after a week of incubation 

 gave no more colonies than those made at the end of twenty-four hours. Its reaction was alkaline, 

 but not intensely so. 



Inxoluted tigariigar. — Of twenty-three tubes of agar-agar iusolated twenty days and then 

 inoculated with the hacilliis li/plii iibdoniinalis, all except one remained sterile, and neither the 

 bucillns ti/phi alidoiniiiulis iror the li(tciUii.s coH co7nmums grew when inoculated in Stripes ou these 



' Presented to tlir National Academy of Sciences at its meeting October 30. 1894. 



483 



