462 STATE BOARD OF AGRICULTURE. 



a few hours old (i. e. after the reductase had become weak) there was 

 little change in the catalase activity during the next 24 hours (or even 

 48 hours if the extract were kept covered at near freezing). On this 

 account, it was not always necessary to run a check for eacli test in a 

 series when treated extract-samples from the same dilution were used. 

 Instead, a check could be made at the beginning of the series and another 

 check held until the end. If a perfectly fresh extract were used, however, 

 the checks had to be run more often, because the strong reductase present 

 inhibited the catalase a little; and as the former weakened on standing, 

 the catalase was able to liberate more oxygen in a ten-minute period. 

 For example, in one extreme case, 2 c. c. of a fresh extract dilution gave 

 (with 5 c. c. of hydrogen peroxide) in 10 minutes, 54.5 c. c. of oxygen, 

 while 2 c. c. of the same dilution kept at 40° F. over night liberated 61 

 c. c. of oxygen in 10 minutes. In another case using the same method, 

 2 c. c. of a fresh extract-dilution liberated 82 c. c. of oxygen while its 

 check 3 hours later (at room temperature) liberated 34 c. c. of oxygen. 

 It should be added that after this rise due to the passing of the reductase 

 activit}', the ability to liberate oxygen from hydrogen peroxide gradually 

 diminislied during longer periods of time. 



About 75 quantitative tests were carried out by tlie methods described 

 above to determine the effects of certain insecticide agents upon catalase 

 activity. Ilepresentative results of these tests are recorded in Table V. 



In discussing the influence of liydrocyanic acid gas on the oxidasic 

 activity of the insect tissue-extract toward alcoholic guaiac, it was 

 stated that, when the test was made immediately after treatment, the 

 guaiac turned blue very much more slowly than in the check. On the other 

 liand when the treated extract was allowed to stand in the air for a while, 

 the influence of the cyanide gas gradually passed off until the treated 

 extract would oxidize the guaiac almost as rapidly as the check. In 

 other words, there was a partial progressive recovery. Table V shows 

 that this insecticide agent behaved in the same manner toward the hy- 

 drogen peroxide catalases. In the experiment, results of which are given 

 in the table, a little more than G c. c. of extract was kept in a strong 

 cyanide bottle for 17 hours. At the end of that time, it was removed 

 to the open air. After airing only 5 minutes, a test was made with 

 5 c. c. of hydrogen peroxide and in the following ten-minute period 2 

 c. c. of this extract liberated only 5.5 c. c. of oxygen — the check, in the 

 same time, liberated 55 c. c. of oxygen. After airing for 2 hours, 2 

 c. c. of the same treated extract liberated 17 c. c. of oxygen ; and after 

 standing in the air for 8 hours until almost all odor of the cyanide gas 

 had disappeared, 2 c. c. of the treated extract caused 26.2 c. c. of oxygen 

 to separate from the 5 c. c. of hydrogen peroxide in a ten-minute period 

 — the check giving 55 c. c. of oxygen. Other tests gave similar results, 

 so that there is no doubt of a partial, progressive recovery of the catalase 

 activity toward hydrogen peroxide in an extract treated with cyanide 

 gas upon standing in the open air. Furthermore, the results of these 

 tests seemed to show that both the soluble and insoluble catalases in 

 the dilute extract had been affected and that both had recovered the 

 greater part of their activity after the passing of the poison. In order 

 to make more certain that this was the case, a few experiments were 

 tried in which hydrocyanic acid gas (from KNO + dilute H^SO^) was 



