CATALA5E AND OTHER OXIDIZING ENZYMES 275 



ment results in an oxidation of chlorophyl, producing yellow 

 foliage. The pale regions in variegated leaves are also associated 

 with the action of these enzymes on the growth of the cells. To 

 this action also some of the autumnal coloration of leaves may be 

 ascribed. The " mosaic disease " of tobacco, and the " brunissure 

 of vines" are examples of the development of unusual amounts 

 of oxidases in the plant. Some of the pathological phenomena 

 in these and other diseases of the plant are due to the interference 

 of the oxidases with the digestion of starch, since it is found that 

 oxidases inhibit the action of diastases, and thus prevent the trans- 

 location of this substance (339). To this fact may be ascribed he 

 accumulation of starch in injured portions of leaves due to ani- 

 mals and fungi. 



352, Demonstration of the Presence of Catalase and Other Oxi- 

 dizing Enzymes. Catalase may be found in almost all animal and 

 vegetable tissues. The material to be tested should be finely 

 divided and put into a test-tube with enough water to cover it, 

 and a few drops of hydrogen peroxide added. If catalase is 

 present bubbles of oxygen will be quickly formed, and will con- 

 tinue to be given off until all the oxygen in the solution is lib- 

 erated. 



Some of the ordinary oxidases and peroxidases may be demon- 

 strated by moistening the freshly cut surface of the tissue to be 

 tested with a two per-cent. solution of gum guiac in 95 per-cent, 

 alcohol. If the more active oxidizing enzymes are present (oxi- 

 dases) the cut surfaces will turn blue. The addition of a little 

 peroxide of hydrogen will increase the intensity of the color if 

 weaker enzymes of this class (peroxidases) are present. En- 

 zymes of the three groups, viz., catalase, oxidases and peroxi- 

 dases usually occur together in most plants. 1 



1 Vines, S. H. On Leptomin. Annals of Botany. 25 : 181. 1901. 



