34 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 21 



color of the cortex, and the quicker it was attained after the latter 

 was ground up. In a few cases, severe treatments very late in 

 the season failed to result in the formation of the brown color, i.e., 

 the untreated material was a darker brown than the treated. 



Results, similar to those just given, were obtained by allowing 

 the cortex material to oxidize the fresh colorless pyrogallol solutions 

 to purpurgallic acid which is a deep cherry red. 1 The methods used 

 and the nature of the results obtained may be illustrated by the 

 following example: After preliminary treatment of the twigs, the 

 cortex was scraped from the wood and ground up. Five grams were 

 added to each of several vials. Some vials received heated cortex, 

 while others received no cortex at all. To each of these vials, 50 cc. 

 of 0.5 per cent freshly prepared pyrogallic acid were added. All 

 were then placed in an oven at 35 C. Observations were made after 

 a few hours. In a specific case the preliminary treatments were, 

 0.5 cc. and 0.25 cc. ether and check. The notes obtained after the 

 cortex material had acted on the pyrogallic acid solution for two 

 hours follow: "In all cases the cortex has settled, leaving the clear 

 liquid above. In every vial, except the one with no cortex, this 

 liquid has separated into two distinct layers, the lower one being 

 yellow, while the upper is reddish brown. In the vials with the 

 untreated material, the upper brown zone is not quite so broad as 

 the lower; in the 0.25 cc. ether vial, the upper layer is about twice 

 as broad as the lower; and in the 0.5 cc. ether vial, the upper layer 

 is three times as wide as the lower. The yellow layer is the same 

 shade in all cases. The upper layer grows darker as it becomes 

 broader, being lightest in the untreated and darkest in the 0.5 cc. 

 ether mixture. After ten hours all vials were uniformly colored. 

 The yellow layer disappeared entirely and the liquid was very opaque. 



This method of determining the oxidizing activity of the twig 

 tissue is probably a little more quantitative than the one given 

 previously. 



In this connection it might be mentioned that treatments which 

 caused the cortex to become deeper brown than that of untreated 

 material, usually caused an earlier growth of the buds. When the 

 difference in color between treated and untreated cortex was slight 

 or not noticeable at all, the treated buds opened just about the same 

 time as untreated. In those cases where the cortex from treated 

 material did not become as brown as non-treated cortex, the untreat- 

 ed opened before the treated. 



1. KastleandShodd. Phenolphthaleinasa Reagent for Oxidizing Ferments 

 Amer. Chem. Journ. (1901) 26. pp. 526-539. 



