458 STATE BOARD OF AGRICULTURE. 



fresh extract of Passalus cornutus. The influence of strong gasoline- 

 vapor upon the reductase was decided and much more marked than any 

 inlluence upon the oxidase-activity — furthermore, the resultant-effect of 

 gasoline-vapor upon the oxidasic action in very fresh extract was plainly 

 due, in part, to the deleterious effect upon the reductase, since the latter 

 was an inhibitor of the oxidasic processes. It Avas evident that in 

 nearly elminating the reductase activity in the treated portion of a fresh 

 extract, gasoline-vapor removed at once a greater inhibiting influence 

 upon oxidasic action than it could itself exert — while in the check portion 

 of the extract this inhibiting influence of the reductase continued for a 

 few hours until it gradually disappeared through standing. Hence, a 

 short period test of oxidase activity was sure to show that most oxygen 

 had been taken up by the gasoline treated portion of a fresh extract. On 

 the other hand, when the test with gasoline-vapor was made with extract 

 that was a few hours old before the test began (and had thus already 

 lost its strong reduction-activity) the inhibiting influence of the gasoline- 

 vapor upon oxygen absorption in the ''extract plus hydroquinone'' solu- 

 tion became readily apparent in either long or short period tests. Thus, 

 an explanation was afforded of those apparently contradictory results 

 obtained when studying the action of gasoline-vapor ui)on hydroquinone- 

 oxidase activity. 



Table IV hardly shows the true extent of the deleterious effect of 

 carbon disulphide upon the reduction-activity of fresh extract — since, 

 in making check studies, it was found that methylene blue was slowly 

 reduced by carbon disulphide alone, in the absence of air. However, 

 that insecticide had little or no effect on indigo carmine, and when the 

 latter was used as the test ageilt (!/•> grm. in 100 c. c. dist. water), it 

 appeared that carbon disulphide Avas much more decidedly harmful to 

 the reduction-activity of the extract than the study with methylene blue 

 would lead one to believe. 



It will be noticed from the table also that the amount of ether-vapor 

 taken up by a water extract seemed to slightly increase or stimulate the 

 reduction activity — whereas a small amount of liquid ether shaken up in 

 the extract brought about noticeable deterioration in the reduction 

 power. On the other hand, immediately upon being added in small 

 amounts, a slight drop in the reduction-activity was caused by sodium 

 fluoride, but after that it tended very markedly to preserve the reducing 

 power of an extract (Nos. 24, 25 and 2G of Table IV). 



The table (IV) itself, perhaps, gives sufficient explanation of the 

 results for the remainder of the agents tested in this connection. 



(c) EFFECT UrON THE CATALASES. 



Brief mention has already been made of the presence of soluble and 

 insoluble catalascs in the tissue-extract of Passalus cornutus. Loew 

 found that the alpha (i. e. insoluble) catalase of tobacco was slightly 

 soluble in water after a time, and this appears to be true of the corres- 

 ponding catalase in the insect tissue extract. The soluble and insoluble 

 catalases seem to be affected alike by heat and other agents, except 

 that the insoluble form is a little more resistant in most cases. The 

 tissue-pulp or crude water extract of P. cornutus may be dried without 

 destroying the nbiliiy to liberate oxygen from hydrogen peroxide, but 



