1917] CURRENT LITERATURE 523 
jt than with it. The data presented for ‘‘tulip tree leaves 1915” and “scaled 
tulip tree buds” show that when the solution in the oxidase apparatus had the 
natural reaction of the plant material, the oxidations were respectively 6.6 
nd 12 per cent greater than when the Cn, established by a buffer solution, was 
actually less than the natural Cn. In such a case it seems evident that some 
factor other than the hydrogen-ion concentration was effective as an inhibitor. 
The possibility that other ions play a part is indicated by work now being 
carried on by KRAYBILL and the writer. 
The paper concludes with a brief review of the evidence, obtained by 
BUNZELL and others, of an increased oxidase activity in the leaf tissue in the 
case of physiological disturbances, and the possible meaning of such an increase. 
No mention, however, is made of work by RosE on healthy and diseased apple 
bark in which it was shown that there is a much greater oxidase activity in the 
latter, sail with a lower hydrogen-ion concentration. 
9 in a paper published about the same time as BUNZELL’s, puts the 
inhibiting Ch for oxidase of potato extract at 5.5x10~4 (slightly higher than 
the 2.0—2.8X10~4 found by BUNZELL), and for that of Red Astrachan apples 
at 5.0—7.0X10—4. His statement that these concentrations are much lower 
than those given by previous investigators fails, however, to take account of 
BERTRAND’S report’? in 1907, that a n/s5o00o solution of sulphuric acid (Ch= 
51074) completely inhibited oxidation by sap of the lac tree. REEp’s results 
would have meant more if he had measured oxidation by the BUNZELL appa- 
ratus rather than by the relatively inaccurate method of noting color changes, 
even though the BUNZELL apparatus, because of the poorly understood effects 
of hydrogen-ion and other inhibitors, leaves much to be desired in the way of 
accuracy, 
One point is well made in this paper, namely, that plant extracts have an 
acid absorbing power which must cause inaccuracy in interpreting results 
obtained by adding buffer solutions to them if such results are not checked by 
careful determinations of the cab ig al ape ranean He found that 
when a given volume of 0.01 molar HC added to an equal volume of 
potato extract, the hydrogen-ion ican rg which should have been 
5X107—3 if the potato extract acted like water, was actually only 51074, 
This decrease in acidity he thinks is due to riecteise present in the extract as 
well as other amphoteric electrolytes, including probably phosphates and 
carbonates. 
It is unfortunate, to say the least, that the authors of these papers have 
failed to cite adequately the literature pertinent to the phase of the subject 
with which they are dealing. Each has made a definite contribution to our 
9 Reep, G. B., The relation of oxidase reactions to changes in hydrogen-ion con- 
centration. Jour. Biol. Chem. 27: 299-303. 1916. 
© BERTRAND, G., Bull Soc. Chim. France 1:1120. 1907. 
