210 abstracts: biological chemistry 



Nearly all of the experiments made thus far have not been carried on 

 quantitatively because of the lack of satisfactory methods. 



The method described is based on oxygen absorption. For this rea- 

 son a constant temperature is essential. The apparatus in which the 

 oxidations are carried out is shown in the text figure. Eight cubic 

 centimeters of the solution of the substance to be oxidized are meas- 

 ured in the pipette and allowed to run into the compartment B. The 

 plant juice, the oxidizing power of which it is desired to study, is meas- 

 ured in pipette F and run into compartment A. Basket H holds 1 

 cc. of normal sodium hydrate to absorb the carbon dioxide formed in the 

 process; M is a manometer charged with mercury to indicate the pres- 

 sure within the oxidase apparatus. The whole apparatus is clamped to 

 a specially constructed shaking machine. In the air-thermostat the tem- 

 perature is brought to 37° C. and maintained at that point to within 

 0.1° thruout the experiment. Half an hour after the temperature of 37° 

 is reached, all stopcocks but I closed, and a shaking machine set into 

 operation. The plant juice mixes with the oxidizable material and the 

 reaction begins. From time to time the shaking is interrupted and ma- 

 nometer is read. In the course of several hours the oxygen absorption is 

 completed, as indicated by no further change of pressure within the flask. 

 The ultimate reading expresses the oxidase content of the juice or ex- 

 tract towards the particular substance used. As a unit an oxidase solu- 

 tion is chosen of such a strength that 1 liter of it will be capable of bring- 

 ing about the consumption by pyrogallol of the equivalent of 1 gram of 

 hydrogen. 



So far pyrogallol, tyrosin, hydrochinone, guaiacol, benzidine, and 

 alphanaphthol have been used in the experiments. The concentration 

 of the material to be oxidized has no effect on the end result provided it 

 is used in excess. The carbon dioxide produced is absorbed by the alkali 

 in the basket and may be determined at the end of the experiment by 

 means of a special apparatus devised for the purpose. The result ob- 

 tained is directly proportional, or at least nearly proportional, to the 

 concentration of the oxidase present. 



The method described was used successfully during the summer of 

 1911 at Utah in the study of the curly-top disease of sugar beets. In 

 this study a very striking fact was brought out. It was found that the 

 plants suffering from the curly-top disease have leaves with a much 

 higher oxidase content than the normal, similarly, an unusually high 

 oxidase content was observed in plants whose growth was stunted for 

 other reasons, such as excessive watering, drought, or failure to pro- 

 duce seed. H. H. B. 



