igoSJ SCHREINER £^ REED— TOXIC PLANT CONSTITUENTS 



7 



I per cent, solution of glycocoU was harmful to yeast and that i per 

 cent, solutions of leucin and aspartic acid were assimilated when 

 carbohydrates were present, but asparagin was assimilated even in the 

 absence of carbohydrate. As classed by Loew ('99), alanin, leucin, 

 asparagin, and glycocoU form good sources of carbon for bacteria 

 a classification which is sustained by the result of numerous investi- 

 gations upon the nutrition of bacteria. Nakamuila. ('96) also showed 



t 

 ^■x 



Fig. I 



that asparagin was a favorable nutrient for barley seedlings. Kiebs 

 ('96) found that i per cent, solutions of asparagin and glycocoU 

 inhibited zoospore formation in Conjena m Inor. 



Our experiments showed that leucin and asparagin are not at all 

 toxic to wheat seedlings. Alanin and glycocoU were slightly injurious 

 at the higher concentrations. Aspartic acid was rather toxic, prob- 

 ably due to its acidic qualities. TyTosin was more toxic than any of 

 the other amino-acid compounds tried {fig. i). At the expiration of 

 eleven days plants in a solution of t}Tosin containing i6 ppm. showed 

 marked injury. At a concentration of loo ppm. it killed the roots and 

 injured the tops of the plants. At a concentration of. i ppm. there 



