iQoS] SCHRFJNER &- REED— TOXIC PLANT CONSTITUENTS 87 



stronger solutions had oxidized part of the arbutin to an insoluble, 

 light-yellow dye which was deposited upon the roots. When the 

 experiment was discontinued at the end of twelve days, the plants in 



000 



The 



of these plants were discolored at the tips and had become slimy. ^ 

 The plants in solutions containing 100 and 25 ppm. were alive, but 

 had made much less growth than the controls in distilled water. 

 The plants in the solutions containing x ppm. of arbutin had been 

 stimulated to make sliffhtlv better growth than the control olants. 



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TLy -■>- r'l^' ^ ' 



y ■' ■" J ■" iZ_ 



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hi^r> -" ^ 



f 



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Fig. ^ 



Vanillin, the aromatic principle of the vanilla bean, is a methoxy- 

 ether of protocatechuic aldehyde. It probably does not occur as 

 such in plants, but exists in the form of a ^ucoside which breaks 



orsrans 



Klebs (^96) found that saturated and ha If -saturated solutions of 



xpcnments 



vanillin were fatal to Conjen:a mhior. 



that wheat seedlings were killed in nine days by solutions conraining 



1000 and 500 ppm. of \-anillin. In solutioos containing 100 ppm. of 



ma 



sometimes 



cfrowth 



