Catalysts of Organic and Inorganic Origin. 319 



penetration is assured. Hence the organic oxidases are possibly proteids, 

 with or without oxidase metals, in basic or acid combination. 



There is no justification for the use of such terms as "peroxidase," 

 " katalase," " oenoxydase," or " tyrosinase," to indicate specific substances, 

 ferments, or groups of ferments. The " tyrosinase " of the potato is also a 

 '■' katalase," a " peroxidase," a " pyrogallase," a " hydroquinonase," and a 

 • : paraphenylendiaminase." It is, however, permissible to use such terms as 

 katalase action or peroxidase action, and such names as laccase, russulase, 

 potatase, carrotase, etc., as temporary names to indicate the origin of the 

 substances, whose chemical nature is yet unknown. Since, however, their 

 oxidase powers will be only one of many properties, it will never be 

 advisable to name them according to these properties alone, any more than 

 it would be in the case of the metallic oxidases. Comparison with metallic 

 oxidases shows that we are not even on safe ground in assuming the 

 existence of specifically distinct classes of plant oxidases, such as phenolases, 

 aminoxidases, and iodoxidases. 



The chlorides and phosphates of potassium and sodium are able to act as 

 oxidase sensitisers, and thus may influence special oxidations, or respiration 

 in general. It is possible that they may exert a stimulatory or controlling 

 action on plant metabolism, and that the sodium chloride always present in the 

 ash of plants may not be an entirely useless constituent. This may explain 

 partly why small doses of salt stimulate the growth of many plants, and 

 why phosphates, in addition to being food substances, may act as stimuli to 

 growth. The stimulating action of many metallic salts on growth may be 

 partly due to their oxidase action. 



Ursol tartrate turns lignified walls red or reddish-brown. This is not an 

 oxidase reaction, but is an admirable test for lignin, especially valuable for 

 demonstrating the wood elements in pulpy tissue. 



Chloroform strongly, and ether more feebly, retard or inhibit katalase 

 action, but they do not suppress oxidase action. After prolonged contact, 

 however, the organic oxidases are slowly attenuated and destroyed. 



The liberation of iodine from potassium iodide may be used as a test for 

 the presence of oxidases in living tissues, but does not indicate the existence 

 of any power of producing peroxides. Dried organic oxidases may retain 

 their properties for three weeks or more, and a glycerine extract for five or 

 more months. "Where organic oxidases are destroyed by boiling, this is 

 probably the result of proteid coagulation. 



The oxidases of the beetroot and potato appear to be related to one 

 another, and to be among the strongest plant oxidases, and the nearest 

 analogies to them are perhaps afforded by ferric salts and ferricyanides. If 



