ipoS] SCHREINER ^ REED— TOXIC PLANT CONSTITUENTS S3 



Monatomic phenols.— Thenol (carbolic acid) is well known on 

 account of its toxic properties^ and an enumeration of the literature 

 dealing with its toxicity would be superfluous at this place. Suffice 

 it to say that True and Huxkel (^98) found that a concentration of 

 w/400 phenol prevented the growth of lupine roots. This concentration 

 would be about 235 ppm. and stands quite near the concentration 

 (250 ppm.) which was required to bring about the death of wheat 



plants subjected to it for eight days. 



The w^heat plants made a small amount of growth before death 

 in solutions containing 500 and 250 ppm. In solutions containing 

 IOC and 50 ppm. the tops wxre alive at the end of eight days, but the 

 roots were dead. The plants in solutions of 5 ppm. were slightly 

 poorer than the control plants, but those in i ppm. were fully as good 



as the control plants. 



Diatomic phenols.— VyToca^te chin (ortho-dioxybenzcne) has been 



reported in a number of different plants. According to Wee\trs 

 (:03) it occurs in several species of wiUows and the characteristic 

 black color which the leaves of certain species of wfllows assume upon 

 drying is probably the result of the oxidation of the p}TOcatechin 

 through the activity of an oxidase. Yabe C94) found that pyro- 

 catechin was fatal to veast ceUs and bacteria when used in concentra- 

 tions of 0.4 to 0.58 per cent. Trce and Hunkel ('98) found that 



catechiUj i, e., about 137 ppm. 



Rowing 



kin^ 



and injured by solutions containing as low as 25 ppm. The stronger 

 solutions became dark colored after standing a few days and were 

 undoubtedlv somewhat more toxic on that account, as was pomted 

 out bv Trto and Huxkel ^98). At the conclusion of the experi- 

 ment ^he roots of the plants were colored purplish brown by the 

 stronger concentrations. The effects of different concentrations ot 



p}Tocatechin are represented in fig- J. . 



Resorcin (meta-dioxybcnzene), which appears to be more stable in 

 solution than pjTOcatechin, is less toxic than that compound. True and 

 Huxkel ('98) found that the growth of lupin roots was prevented by 

 m/200 solution (about 55° Ppm-), thus exhibiting less toxici^ than 

 pyrocatechin. B v our method of experimentation we found that the 

 lowest concentration causing death was 1000 ppm. In concentration. 



