PRESENT STATUS OF THE PROBLEM OF THE 

 EFFECT OF RADIUM RAYS ON PLANT LIFE* 



C. Stuart Gager 



Brooklyn Botanic Garden 



The discovery of radioactivity during the last decade of the 

 nineteenth century at once raised the interesting question, not 

 "will it act as a stimulus to plant life," but "in what manner, and 

 to what extent will it affect the various life functions?" Experi- 

 mental inquiry established conclusions that any physiologist might 

 have formulated a priori. As with any other form of energy to 

 which plants are normally adjusted — viz., heat, light, gravitation, 

 electricity, oxidation, and other chemical actions — radioactivity, 

 within certain limits of intensity, favorably affects any physio- 

 logical process, causing an acceleration of it up to a certain point — 

 the optimum; beyond that point the stimulus is too great, and 

 the attempts at response result in retarded or unregulated func- 

 tioning, disorganization, disease, and death. 



In volume III of the Memoirs of The New York Botanical 

 Garden, "Eft'ects of the rays of radium on plants," published in 

 December, 1908, this was experimentally demonstrated for 

 practically all the processes of plant life — germination, growth, 

 respiration, irritability, cell-division, synthesis of carbohydrates, 

 fermentation, and others. 



Since that publication, several workers — chiefly in Europe — 

 have, from time to time, issued papers of various length, on the 

 effects of radium-rays on plants; but a careful reading of nearly, 

 if not all, of the literature has failed to disclose any real addition 

 to our knowledge of the subject since 1908. Other plant material 

 has been used, and results have perhaps, in some cases, been 

 stated in more accurate quantitative terms; but the net results of 

 all investigations may still be accurately summed up by the 

 brief statement that sufficed in 1908, viz.. The rays of radium 



* Brooklyn Botanic Garden Contributions No. 15. , 



153 



