7^ BOTANICAL GAZETTE [February 



The photographs which are appended show in a general way the 

 growth of the plants in comparison with the controls. 



The investigations here reported were intended to reveal the char- 

 acter of the toxic action of the several compounds rather than to estab- 

 lish the exact limits for then: toxicity. Strict mathematical accuracy 

 is not claimed for the data, but it is believed that they mdicate correctly 

 the order of the results, and that, within the experimental error, they 

 approach the toxic limits for each compound. A general summary 

 of the results is presented m Table II and the details are described in 

 the following pages. This table shows the lowest concentration of the 

 compounds which caused the death of the wheat plants, provided 

 they were killed by a concentration of looo ppm. or less; the lowest 

 concentration causing injur}^; and the concentration causing stimu- 

 lation, where such a phenomenon was observ^ed. 



It would be manifestly improper to make strict comparisons 

 between these results and those obtained by other investigators who 

 determined the concentration necessary to kill or prevent growth in 

 twenty-four hours or less. Obviously, a concentration which is sufS- 



of several days. 



mav 



Experimental results 



THE ACTION OF SOME SIMPLE AXD SUBSTITUTED AMINO- ACIDS 



Recent researches upon the chemistr}^ of proteids have brought 

 the amino-acids into prominence physiologically. These bodies are 

 found in relatively large amounts in plants, especiaUy in those of the 

 legume and mustard families, not only in the seedling stage of the 

 plants but also in the roots, stems, and storage organs of mature 

 plants. According to Dojarexko (:o2) the amino-acid nitrogen 



forms a \^ry considerable portion of the nitrogen of humus bodies 

 (22 to 70 per cent.). 



The action of amino-acids upon plants has been studied by a num- 

 ber of !r:-:stigators. Asparagin (amino-succinic acid) has received 

 the most attention because of its importance as a nutrient for hetero- 

 trophic plants. Maiek ('69) demonstrated the mlue of asparagin 

 as a nutrient for f unni. T 



o 



AUHENT (»9o f Studied the effect of gl; 

 asparagin upon yeast. He found 



