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U. SUZUKI. 



difference became very noticeable, sometimes the difference 

 was heightened when the extract was heated to jo°C for five 

 minutes, thus retarding the activity of oxidase. But except in 

 a few cases, this procedure was hardly necessary, the differences 

 being plainly noticeable. 



b) Peroxidase. 



Peroxidase, as already mentioned, does not produce a 

 blue colour on simple addition of guaiac tincture, but it requires 

 also some hydrogen peroxid. It always accompanies oxidase 

 in the mulberry leaves. Its resisting power against heat is, 

 however greater than that of the latter. After destroying the 

 oxidase at 75 — 8o°C, the peroxidase can still produce a 

 distinct blue coloration with hydrogen peroxid and guaiac 

 tincture. The coloration was always much darker than that 

 of the oxidase and somewhat greenish. We can also prove 

 the presence of peroxidase when mixed with oxidase by properly 

 diluting the extract. Thus, the extract was divided into two 

 parts, to one portion was added only guaiac and to the other 

 guaiac and hydrogen peroxide. After a few minutes, a very 

 marked difference was observed ; the blue coloration being 

 several times more intense in the latter. Further, by heating 

 to 70 C C, the power of oxidase is largely weakened and the 

 subsequent addition of hydrogen peroxid produces a distinct 

 difference after a few minutes. The opinion of Spitzer, that 

 peroxidase can cause the developement of oxygen from 

 hydrogen peroxide is erroneous, since the activity of catalase, 

 i.e., the power of decomposing hydrogen peroxid, is entirely 

 lost by heating to 70 — 75 C C for five minutes, while still a 

 distinct blue coloration may be produced by the addition of 

 guaiac and hydrogen peroxid. 1 In the mulberry leaves I found 

 always a good deal of peroxidase. The comparison of the 

 peroxidase reaction in healthy and diseased leaves showed the 

 following result : 



Oct. 27. gathered at Nishigahara. 



1 Hydrogen peroxide is for our purpose conveniently prepared by dissolving b grams 

 of sodium peroxid in ico c.c. water and exactly neutralizing this solution with dilute 

 sulphuric acid. 



