CELL-CONTENTS AND FORMS OF CELLS. 245 



stances taking part in the reaction. Zymases are widely dis- 

 tributed throughout the entire plant kingdom, and occur in 

 greatest amounts in yeasts and other organisms which induce 

 alcoholic fermentation. The enzyme, which causes the transfor- 

 mation of glucose into lactic acid and is secreted by lactic acid 

 bacteria, has been given the name of " lactic acid bacteria-zymase." 



Oxydases is the name applied to those enzymes in which the 

 decomposition or reaction involves an oxidation. Several kinds 

 of oxydases are recognized, depending upon the nature of 

 the original substance that is broken down, (i) Alcoholase, the 

 enzyme of acetic bacteria which oxidize ethyl alcohol to acetic 

 acid. (2) Phenolases include the laccases, the oxidizing enzymes 

 found in the lac-tree {Rhus succedanea), and in some other 

 plants. The black lacquer covering the beautiful Japanese vases 

 and boxes, and which is the most indestructible varnish known to 

 man, is formed by an oxidizing enzyme acting on the phenolic 

 resins of the lac-tree. 



Catalases in their chemical action resemble some of the col- 

 loidal metals, in that they are able to decompose hydrogen 

 peroxide with the liberation of oxygen. Enzymes of this char- 

 acter have been found in virtually all plant juices. Catalases are 

 of two kinds, one soluble in water, occurring in the seeds of apple 

 and peach, and an insoluble form found in the leaves of clover, 

 rose, and spruce. Highly active catalases are also obtained from 

 fungi, yeasts, and bacteria. 



While some of the vegetable ferments have been isolated and 

 are prepared on a commercial scale, as diastase and the t^eptic 

 enzyme papain found in the latex of Carica Papaya, in other 

 cases the ferment-producing organisms themselves are used in 

 a number of industries involving fermentation processes, as the 

 yeast-plants and certain of the molds and bacteria. 



The microchemical study of the ferments is attended with cer- 

 tain dif^culty on account of the lack of specific reagents for their 

 detection. The most that can be done is to study the products 

 formed by their action upon certain other constituents of the cell. 

 (Consult " General Chemistry of the Enzymes," by Hans Euler, 

 translation by Thomas H. Pope.) 



