Scientific Proceedings. 



(■so 37 



they are retarded. Seeds are less sensitive to the rays when dry 

 than when soaked. When germinating seeds are exposed to 

 radium at short distance, germination and subsequent growth are 

 retarded, but when the distance between the radium and the seeds 

 is increased and a screen of metal is interposed, growth is acceler- 

 ated. Radium rays acting through soil in which plants are grow- 

 ing accelerate both germination and subsequent growth of the 

 shoot, and increase the number and length of root hairs. 



The growth of plants is retarded in an atmosphere of decaying 

 radium emanations, such as may be drawn from tubes lined with 

 Lieber's " radium coating." [See page 32 (96).] Development of 

 leguminous tubercles is retarded when a glass tube of radium 

 bromid (10,000 activity) is in the soil. Experiments to obtain 

 radiotropic response have so far given negative results. Alcoholic 

 fermentation is accelerated by radium rays. 



Chloroplasts, under the influence of the rays, change their 

 position in the cell, as when exposed to too intense sunlight. 

 Plastids are soon over-stimulated, and their activity completely 

 inhibited, causing etiolation and other attendant effects. Gemmae 

 of Lunularia, exposed for six days, failed to develop thalli. Men- 

 stem (embryonic tissue) of the hypocotyl is destroyed by prolonged 

 exposure to the rays. 



II. " The action of radium rays on Amoeba protetis and upon 

 other microorganisms " : Louis Hussakof (Laboratory of Zoology, 

 Columbia University, and the American Museum of Natural 

 History). 



These experiments were intended primarily to show the influ- 

 ence, if any, of radium rays on the protoplasm of Amoeba proteus. 

 Other microorganisms ( Vorticella, Paramecium, etc.) were also sub- 

 jects of experiment. Radium bromid preparations of 600, 1,000, 

 10,000, and 1,500,000 activity (in thin glass tubes) were used, and 

 several celluloid rods covered with Lieber's "radium coatings' 

 [page 32 (96)] of 10,000 to 25,000 activity were also employed. 

 The radium container was held in the water within from 1 mm. 

 to 3 mm. of the organism under observation. 



Lender these conditions no visible effects were produced, by 

 even the strongest radium preparations, during periods of observa- 

 tion of about an hour. The water surrounding the animal may 

 have prevented radiant effects. 



