. Botanical gazette. Plants. iqiq] ROSE—BLISTER CANKER 129 Further study is necessary to show the facts. A test of these pre- cipitates with pyrocatechin showed that while the 2 fractions from healthy bark are about equal in oxidizing power the first fraction from diseased bark is 11 times as active as the second (fig. 7).. Fig. 7.—Oxidation of pyrocatechin by precipitated oxidases from healthy bark, without gelatine: A, fraction i; B, fraction 2; C, fractions i and 2 tested together; D, sum of fractions i and 2 tested separately. Other precipitates were prepared using 25 cc. of alcohol for th
. Botanical gazette. Plants. iqiq] ROSE—BLISTER CANKER 129 Further study is necessary to show the facts. A test of these pre- cipitates with pyrocatechin showed that while the 2 fractions from healthy bark are about equal in oxidizing power the first fraction from diseased bark is 11 times as active as the second (fig. 7).. Fig. 7.—Oxidation of pyrocatechin by precipitated oxidases from healthy bark, without gelatine: A, fraction i; B, fraction 2; C, fractions i and 2 tested together; D, sum of fractions i and 2 tested separately. Other precipitates were prepared using 25 cc. of alcohol for the first fraction and 100 cc. more for the second. The oxidase activity of these, tested separately and combined, with and without gelatine, is shown in table XIX. TABLE XIX 0XID.\SE ACTIVITY OF FIRST AND SECOND FRACTIONS FROM B-^RK EXTRACT TESTED SEPARATELY AND COMBINED; TEMPERATURE ° C. Without gelatine With gelatine Bark Sum of fractions I and 2 tested separately Fractions i and 2 combined Sum of fractions i7,„^,.- „„, ^„a -, _ J i »_j iT Tactions I and 2 ' separVte^ --^"-^ Healthy, after 23 hours. . Diseased, "38 " . . ; 1 The mechanism by which gelatine increases the oxidase activity is not clear. It is evidently not through buffer action, as shown by its lack of effect on the hydrogen ion concentration (table XVII, figs. 8, 9, 10). Special tests showed that there was no hydrolysis of the gelatine to amino acids, in either healthy or diseased bark, which would increase its buffer effect. If gelatine is effective through its action as a protective colloid, its effect in this direction must be very complex, as shown by its difference in effect on bark mixtures and precipitated Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the o
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