454 DESTRUCTION OF TYPHOID AND COLON BACILLUS. 



otlier iu a similar tube covered with black paper. The materials used 

 for making the colored solutious were corallin, chromate and bichro- 

 mate of potassium, and methylene blue. From these tubes plates were 

 made, and the number of colonies counted. 



It was found that an increase in the number of colonies continued to 

 the eighteenth day, tbe number being greater in the colon and aureus 

 cultures than in the tyi)hoid. The colonies then began to decrease, and 

 on the tifty-eighth day tbe plates contained but few colonies. In tliis 

 experiment, as in the last, plates made from culture tubes i)]aced iu 

 blue fluid showed fewer colonies. 



Since the presentation of the above results, with details, charts, and 

 tables, to the National Academy, in April, 1894, Dr. Dieudonne has 

 published, in the Arbeiteu aus dem Kaiserlichen Gesundheitsamte, a 

 paper on the effects of sunlight on bacteria, in Avhich he reports results 

 substantially the same, and obtained by almost the same methods as 

 those of Dr. Peckham. 



Sunlight not only weakens or kills the typhoid and the colon bacillus, 

 but it aftects culture media so as to render them less capable of sup- 

 porting the growth of these organisms. Dr. Peckham found that 

 sterile bouillon insolated from one to ten days and then inoculated with 

 the bacilbis typhi abdominalis showed no diminution in the number of 

 colonies as comi)ared with a control plate made from a similar culture 

 not so exposed. Twenty days insolation and then inoculation with the 

 typhoid bacillus showed great, decrease in the numbc^r of colonies on 

 all the i^latesj some of them were 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 insolated fifty to sixty days and 

 inoculated gave sterile tubes. This insolated bouillon after inoculation 

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

 of incnbation gave no more colonies than those made at the end of 

 twenty-four hours. Its reaction was alkaline, but not intensely so. 



Insolated agar-agar. — Of twenty-three tubes of agar-agar insolated 

 twenty days and then inoculated with the bacillus typhi abdominalis, 

 all except one remained sterile, and neither the bacillus typhi al)dom- 

 inalisnor the bacillus coli communis grew when inoculated in stripes on 

 these i)lates. Of seven tubes of agar-agar insolated forty days and 

 then inoculated with the bacillus of typhoid, all remained sterile. On 

 fomr of these plates mold appeared after some days. Of seven tubes 

 of agar-agar insolated forty days and then inoculated and incubated as 

 before, all remained sterile. 



Insolated gelatin. — Of ten gelatin tubes insolated forty days and then 

 inoculated with the bacillus typhi abdominalis, six remained sterile, two 

 contained a few colonies of bacillus typhi abdominalis, and two were 

 contaminated. 



