S8 BOTANICAL GAZETTE [February 



The roots of the plants growTi in the stronger solutions oxidized 

 some of the vanillin to a purplish-browTi, insoluble dye, which colored 

 the roots. The general character of the oxidation has been described 

 in a prelimmary communication by Schiieiner and Reed (:07c). 



Vanillic acid, a monomethylprotocatechuic acid, showed greater 

 toxicity to wheat plants than vanillin. The plants were killed in seven 

 days in solutions of 100 ppm. or stronger. In solutions containing 

 25 ppm. of vanillic acid, the only inferiority noticed in the plants was 

 their root development ; but the plants grown in concentrations of 5 

 and^ I ppm. were better than the controls in distiUed water. Although 

 vanillic acid is more toxic to wheat plants than vanillin, it appears to 

 be less inhibitory of root development. 



^ Chinone (benzochmone) may be prepared artificially from quinic 

 acid or from hydrochinone. It is a compound of interest in the study 

 of son problems since Beijeeinck (:oo) has found that a soil fungus, 

 Streptothrix chmnogena, has the ability to form chinone from proteids. 



Chmone has been shown to be toxic to the seedlings of various 

 plants, algae, and fungi by Furuta (:o2). In concentrations of 

 1000 and 500 ppm. the roots of soy bean and wheat seedlings were 

 mjured within a few hours and kiUed in three or four days. Fila- 

 ments of algae were kiUed in a concentration of 1000 ppm'. in three 

 or four hours, and fungi in a somewhat longer period. 



Chmone is one of the most toxic compounds whose effect upon 

 wheat seedlings was studied. A concentration of 100 ppm. was fatal 



and even i ppm. produced an iniurious effect. In the 



nm, ^„ 



intermediate 



rhe plants scarcely survived in a concentration of 50 and 25 ppm. 

 and only in concentrations of 10 and i ppm. was there anv growth 

 comparable to that of the controls in distiUed water. 



The great toxicity of chinone is probablv due to two of its 

 chemical properties. The first of these is its strong oxidizing power, 

 by virtue of which it is probably able to oxidize labfle compounds 

 which exist in cells of the plants and render them unsuitable for use 

 m metabolism. The second property which gives chinone a toxic 

 action is Its ketone nature. Chinone readfly forms bromin addition 

 products. It umtes with one molecule of hydroxykmin to form chinon- 

 oximc; with two molecules of hydroxylamin it forms chinondioxime. 



