82 BOTANICAL GAZETTE [February 



1- 



the p}TidiTi ring by condensation, but rather that it exists already in 

 some form in the soil." P\Tidin was also obtained from the same 

 soil after extraction with ether, hence it seems that the view taken is 

 the correct one. 



In the experiments with wheat seedlings it was found that p\Tidin, 

 although not sufficiently toxic at a concentration of looo ppm. to kiU 

 wheat plants in nine days, was nevertheless very injurious, especially 

 to the growth of the green parts of the plants. In a concentration as 

 low as 50 ppm. the growth of the tops was inhibited and the leaf- 

 tips turned brown. In the lower concentrations there was no stimu- 

 lation of growth. 



Picolm (C5H4N-CH3), or methyl p\Tidin, was toxic to wheat plants 

 but acted fatally only in the concentration of 1000 ppm., and caused 

 mjury at 500 ppm., but not in lower concentrations. The injury 

 seemed to be manifested by the tops more than by the roots, thus 

 resembling the action of pjTidin. 



. ^^F^idi^ (CsH^.X), or hexahydropyridin, differs in chemical con- 

 stitution from p}Tidin by having two atoms of hydrogen attached to 

 each carbon and one atom of hydrogen attached to the nitrogen atom. 

 Solutiom of piperidin kiUed and injured at a lower concentration than 

 either pyridin or picolin. A sample of piperidin, which was neutral- 

 ized With acetic acid, proved to be more toxic than the stronglv alka- 

 line piperidin itself. Piperidin seemed to injure the roots more 

 severely than the tops. By reference to Table I, it wiU be seen that 

 pipc-ndm is more toxic than pyridm, a fact which may be due to the 

 additional hydrogen it contains. 



Chinolin (C.HyN) forms the nucleus of manv alkaloids found in 

 plants belonging to the families Rubiaceae and Loganiaceae. Falk- 

 ENBUKG C91) found that chinolin was toxic to bacteria in a concen- 

 traton of 2000 ppm. Reference to Table H shows that chinolin was 

 efficiently toxic to kiU wheat plants at a concentration of 500 ppm. 

 bo low a concentration as 5 ppm. affected them injuriously in sLx days, 



caused stimulation 



PHEXOI 



jmrt of the phenols used 

 make the stndv mnr^ ^*-.ty>^i 



results 



