188 Scientific Proceedings, Royal Dublin Society. 



EXPLANATION OF PLATE XVI. 



PLATE XVI. 



Fig. 



1. Plate culture of Bacillus pyocyaneus, exposed in the cold for four 



days to the tube containing 5 mgrs. of radium bromide, distant 

 10 mm., and incubated in presence of the radium for three 

 days at 22° C. 



2. Plate culture of B. pyocyaneus, exposed four days in cold to the 



same sample of radium, distant 7 mm., and incubated two 

 days at 22° 0. The dark horizontal line, just below the 

 clear central patch, is the expression of the denser growth of 

 the colonies in the shadow of a platinum rod which inter- 

 vened between the culture and the radium. 



