150 



ship committee, during the summer interruption of meetings, to 

 receive applications for membership accompanied by the fee, and 

 to accord such appHcants all the privileges of regular membership. 



The first paper on the scientific program was by Dr. C. Stuart 

 Gager, and was entitled " Preliminary Notes on the Effect of 

 Radio-activity on Plants." Plants grown in the presence of 

 radium are subject to four different influences : (i) the a-rays, 

 composed of a stream of material particles bearing a charge of 

 positive electricity ; (2) the y5-rays, made up of a stream of par- 

 ticles I / 2,000 the size of those of the r/-rays and carrying a charge 

 of negative electricity ; (3) the ^--rays, analogous to X-rays, but 

 much more penetrating ; (4) the emanation, which in a process 

 of "decay" gives off a-rays as described, and eventually the [i- 

 and /'-rays mentioned above. The emanation behaves like a 

 very heavy gas and may be condensed on a solid surface at a 

 temperature of 150° C. The influence of radium upon plants, 

 therefore, is of the nature of radiant energy. 



The radium was employed in the form of the salt, radium 

 bromide, of three strengths of activity, 1,500,000, 10,000, and 

 7,000, enclosed in sealed glass tubes ; and also in the form of 

 celluloid rods and cylinders covered with Lieber's radium coating 

 of 10,000 and 25,000 activity. The glass shuts off practically 

 all the a-rays ; the /5-rays penetrate through the glass more 

 easily, while the T'-rays pass through glass very readily. By the 

 use of the coated rods and tubes all three kinds of rays as well as 

 the emanation are available. 



The experiments indicate that the rays act as a stimulus, which 

 varies in intensity with the strength and amount of radium used, 

 the thickness of the seed-coats, distance of exposure and the in- 

 tervention of moist soil between the radium and the plant. If 

 the stimulus ranges between a minimum and an optimum, ger- 

 mination and subsequent growth are accelerated. Within these 

 limits the rate of alcoholic fermentation is at first increased, but 

 continued exposure may result in over-stimulation and conse- 

 quent decrease in rate. 



Viy over-stimulation, germination and growth of seeds, gemmae 

 of Ilepaticae, and pollen-grains arc retarded and may be com- 



