380 Journal of Agricultural Research Voi. xv, no. 7 



combined with various metabolic products form very unstable and 

 readily oxidizable compounds, we are of course as yet unable to judge 

 (50) . It is possible that the difference observed was primarily of physical 

 origin. Traube {48), in his paper on catalysis, recognized surface ten- 

 sion as one of the most important factors in the acceleration of bio- 

 chemical reactions. The oxidase activity observed might be due simply 

 to an increased concentration of the oxidizable material or oxygen, or 

 both, in the layers adjacent to certain colloidal particles. 



It is certain that in the course of stunting of growth there is an increase 

 in the effectiveness of the oxidase mechanism. Whether this is the 

 cause or a symptom of the disease is an open question. If we assume 

 with Palladin (57) that with the aid of the respiratory pigments the 

 oxidases are capable of carrying on the process of cell respiration, then 

 it can readily be seen how an increased oxidation of some of the inter- 

 mediate products of metabolism might seriously alter the course of the 

 latter. Such plants could be said to be in a state of "fever" (<?). If, 

 on the other hand, oxidases are merely protective agents, as Portier 

 {38) assumes, then the increased oxidase activity of the diseased plants 

 would have to be ascribed to an attempt on the part of the plant to rid 

 itself of poisonous products formed in the course of its abnormal 

 metabolism. 



