gager: effect of radium rays on plant life 157 



peppers, com, muskmelons, and other vegetables. The radio- 

 active fertiUzer was appHed to four plots of 100 sq. ft. each in 

 amounts of 25, 50, 100, and 200 lbs. respectively. The author 

 concludes (p. 15) that, "The amount of radium required for the 

 greatest results differed with different crops. In five cases 200 

 lbs. per 100 sq. ft. gave the best results, in eight cases 100 lbs., 

 in five cases 50 lbs., and in eleven cases 25 lbs." "Families of 

 plants," the author says, "showed the same varying suscepti- 

 bility." Thus, plants producing underground crops, such as 

 turnips and radishes, gave results analogous to those given by 

 plants with aboveground crops, such as cauliflower, cabbage, and 

 mustard. This statement is of considerable interest in view of the 

 fact, disclosed by laboratory experiments, and recorded by several 

 investigators, that tissues with chlorophyll react to radium-rays 

 differently from tissues without chlorophyll. 



Rusby states (p. 21) that, "The relative effects on the upper and 

 lower portions of a sloping plot have not been uniform. Of ten 

 rows of celery so planted, plants on the lower rows are nearly 

 twice as large as plants on the upper ones, and the transition is 

 gradual and nearly equable. A possible explanation of this," 

 says the author, "is by assuming that in case of a hard rain, with 

 surface drainage, the emanations^ in the water in the soil would 

 quickly diffuse through the surface water and be carried down- 

 ward." 



In this possible explanation two facts are overlooked: i. That 

 freshly fallen rain water is radioactive, and produces physio- 

 logical stimulation to plants, as was demonstrated by experi- 

 ments recorded in the Botanical Garden Memoir above cited. The 

 mere accumulation of this water in relatively larger quantities near 

 the lower portions of a slope might cause differential conditions 

 of radioactive energy, and therefore differential results. 



2, The possibility that the differential results may be attributed 

 solely to the excessive moisture at the lower portions of a drained 

 slope. The plants involved were celery, and celery is well known 

 to thrive in trenches, where there is, of course, more moisture 

 than on a drained surface. The gradual transition in size is 



^ There is only one emanation (a radioactive gas) given off by radium. The author 

 here doubtless means to refer to the ions (streams of which constitute the a and /3 rays 

 of radioactive substances), as well as to the radioactive gas or emanation. 



