l60 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Experiments by Lipman and Blair' with the same compound 

 gave entirely negative results; and Stevens'- from experiments 

 also with the same compound, found that growth was accelerated 

 only when as much as 2I2 per cent of the compound was applied 

 to a soil. To employ it in agriculture in this proportion would 

 take about 25 tons to the acre, which would cost the farmer, 

 per acre, about $5,000. 



In reviewing the literature, it is remarkable to note that in 

 a' most no instances was the so-called radioactive fertilizer tested 

 to see if it was really radioactive, and to what extent; nor was 

 it analyzed chemically to ascertain what elements of plant "food" 

 it might contain. Without making these tests it is folly to 

 attempt to draw any inferences as to the value of radioactive 

 substances in practical agriculture. 



From a large number of experiments on crop plants, Berthault, 

 Bretigniere, and Berthault^ concluded that better results were 

 obtained by combining rildioactive substances with standard 

 fertilizers. None of the results obtained by these authors were 

 considered as due to the known presence of certain chemical 

 compounds which stimulate plant growth; but all results were 

 attributed to radioactivity, notwithstanding the authors' frank 

 statement that, when the compound they used was tested, not a 

 trace of radioactivity could be detected. 



The evidence here briefly re\iewed would seem to justify the 

 broad inference that, although radioactivity may act as a stimulus 

 to plant growth, our present knowledge of the cost of radium, 

 and of its physiological effects, affords little, if any, ground for 

 expectation that it possesses any value for practical agriculture. 



' New Jersey Agr. Exp. Sta. Bull. 269. M\- 29, 1914. 

 ^Stevens Indicator, April, 1914, p. 150. 

 * Vie Agr. ct Riir. 2: 241. 1913. 



