438 STATE BOARD OF AGRICULTURE. 



by most workers in this field as an organic peroxide, or an oxygenase 

 (i. e. a substance capable of quickly forming an organic peroxide by 

 uniting with oxygen from air) working with a peroxidase. The alpha 

 and beta catalases, as demonstrated by Loew, are enzymes which are 

 capable of breaking down n.0„ into molecular oxygen and water, the 

 oxygen coming olT in bubbles. Finally, tissue pulp from plants and 

 from animals has been found to possess a more or less strong reducing 

 power. This power has been generally attributed to reducing enzymes 

 called reductases. Knowledge of the functions and properties of the 

 enzymes mentioned above is, as yet, very incomplete. Satisfactory proof 

 has not been obtained in some cases, and there are those who believe that 

 reductases and catalases are not enzymes at all. As experiments and 

 observations accumulate, however, there seems to be a growing number, 

 among those actively engaged in investigation of the subject, who be- 

 lieve that in the oxidases, catalases, and reductases we have to do with 

 a part, at least, of the machinery which accomplishes oxidations and 

 respiration in the protoplasm of living cells. ' Alexis Bach, for example, 

 has gone so far (in 191.3)*, in a discussion of oxidising and reducing 

 enzymes, as to express his belief in their role in the process of respira- 

 tion rather definitely. E. F. Armstrong in the "Journ. of the Chem. 

 Soc. 104, Part I, p. 543, abstracts Bach's conclusions as follows : 



"(1) In order to utilize the oxygen of the air to effect oxidation, the 

 cell produces an enzyme (an oxygenase) — a substance which is readily 

 oxidized, fixing molecular oxygen to form a peroxide. (2) A second 

 enzyme (the peroxj^dase) accelerates the oxidizing action of the perox- 

 ides, acting on them in the same way as ferrous sulphate does toward 

 H2O2. (3) The peroxides are readily transformed by hydrolysis into 

 HoO, which is also formed as a primai'y product during hydrolytic oxida- 

 tion. Owing to its rapid rate of diffusion, this accumulation of H^O, 

 might damage the cell protoplasrn. To guard against this, the cell pro- 

 duces an enzyme — catalase, which rapidly decomposes HoO, into water 

 and inert O,. Catalase thus acts as a regulator of the respiratory pro- 

 cess. (4) To effect hydrolytic oxidation, an enzyme-perhydridase — is 

 present which accelerates both oxidation and reduction just as do the 

 metals of the platinum group. The reductase consists of the enzyme, 

 water and an oxidisable substance which fixes the oxygen derived from 

 the water, leaving the hydrogen free to effect reduction." 



In view of the importance which physiologists begin to attach to 

 oxidizing and reducing bodies in tissue extracts of animals and plants, 

 and because of the influence which certain of the contact insecticides 

 are now known to have upon the respiratory exchange of insects, it seemed 

 worth while to investigate these bodies in insect tissue extract and to 

 study the effect of gasoline, carbon disulphide, and some other contact 

 insecticides upon the activity of those found to be present. 



(c) OXIDIZING AND REDUCING BODIES IN INSECT TISSUE PULP OR EXTRACT, 



The method used in preparing insect tisue pulp for study has already 

 been described. In preparing the crude extract the pulp was ground 

 up with a small amount of sterile distilled water— usually about twelve 

 to fifteen cubic centimeters to five or six adult specimens of Passalus 



*(Arch. Sci. phys. nat, 1913, vol. 35, 240-262). 



