56 



Effect of Arsenic Compounds 



of 1/1,000,000, but from this point down to 1/250,000,000 a constant 

 depression showed itself, which was paralleled by a similar depression in 



Fig. 12. Curve showing the mean value of the dry weights of ten series of barley plants 

 grown in the presence of arsenic acid and nutrient salts. (Feb. 28th April 24th, 

 1911.) 



Fig. 13. Curve showing the mean value of the dry weights of ten series of barley 

 plants grown in the presence of sodium arsenite and nutrient salts. (Feb. 10th 

 April 18th, 1913.) 



the sodium arsenite series from 1/25,000,000 to 1/250,000,000, the curves 

 grading downwards instead of up towards the normal. With peas sodium 



