EXPERIMENTS WITH RADIUM 93 



The cultures were obtained only when the edge 

 of the glass slide came in contact with the 

 gelatin. 



In looking through some of the literature of the 

 subject, I found that it was a well-known fact that 

 gum acted on gelatin in such a manner as to pro- 

 duce oily drops.^ Controls with gum alone, however, 

 proved that the two effects were entirely different, 

 the gum globules being confined chiefly to the 

 surface, and disappearing altogether after some days, 

 whilst the radium effect increased. 



Thus it seemed quite clear from these control ex- 

 periments that the gum was not the cause of the 

 culture-like appearances, whilst subsequent experi- 

 ments with pure radium salts proved this beyond 

 doubt. 



The next step was to get sub-cultures by inocula- 

 tion in fresh media. The sub-cultures did not show 

 the slightest signs of growth for nearly six weeks. 

 They then, however, did manifest some tendency 

 towards development, but only to a very small 

 extent. 



It was at once evident that the original cultures 



were not bacteria. 



When working some time ago at the phosphor- 

 escent glow in gases, I was led from various con- 

 siderations to infer that the luminosity was the result 

 of great complex molecular agglomerations produced 

 by the spark. The duration of the life-period of 

 those molecular groups, if they might be so called, 



1 Article " Gum," Encyclopedia Britannica, ninth edition. 



