82 



Otis F.- Curtis 



of stimulation, but the optimum results show a root growth 2.41 ±0.10 

 and 1.97±0.l4 times that of the control. Tho but single cultures were 

 used, and there were only five twigs in the sand cultures — except in 

 the check, in which the number was sixteen — yet the results were 

 unexpectedly consistent, showing a continuous change with change in 

 concentration with one unimportant exception in which the culture having 

 a slight increase in concentration had a somewhat lower root length. In 

 four cases the weakest concentrations gave a root length shorter than 



Fig. 1. LIGUSTRUM CUTTINGS AS AFFECTED BY TREATMENT WITH POTASSIUM PERMAN- 

 GANATE 



Upper row; Cuttings treated for twenty-four hours in 1-per-cent KMnOi; the five at the left then 

 Vlaced in sand, the remainder in tap water 



Lower row: Check. Cuttings left for twenty-four hours in tap water; the five at the left then placed 

 in sand, the remainder in tap water 



that in the check. These dilutions were so great and the results so similar 

 to those of the check that the latter may indicate merely a probable 

 variation between separate checks. 



The stimulation here obtained has been fully confirmed by later ex- 

 periments in which duplicate and triplicate cultures were made, and by 

 others in which one hundred or more twigs were used in each treatment. 

 This table was given in preference to the others, as the single experiment 

 covers a wider range of concentrations and lengths of treatment than 

 any one subsequent experiment. 



