192 Scientific Proceedings, Royal Dublin Society. 



PLATE XVIII. 



Fig. 



1. Plate culture of Bacillus prodigiosus. The organism was smeared 



on the surface of the nutrient agar and exposed to the radium 

 at a distance of 4-5 mm. for one day in the cold. The photo- 

 graph was taken after two days' incubation at 22° 0., during 

 which the radium was absent. 



2. Plate culture of Bacillus pyocyaneus. Before incubation a circular 



patch was removed from the agar emulsion, and replaced by 

 sterile agar. After incubation for two days at 37° C. the 

 circular patch was inoculated. The inoculation failed to 

 grow, as is shown by this photograph, which was taken three 

 days after inoculation, during which the plate was incubated 

 at 37° C. In the figure the scratch made by the inoculating 

 rod is more evident than on the plate itself. The bacilli did 

 not develop along this scratch. 



