( 199 * 
of the absence of the guiacum-blue coloration after addition of H,0,. 
They were named after their typical reactions saligenolase and 
catecholase; both gave an almost colourless, somewhat turbid solution. 
They may be separated by heat, for after heating to 85° C., the 
saligenolase had been destroyed* but not the catecholase. Catecholase 
oxydises catechol: a catechol solution which by itself remains unchanged 
for days, changes at once after the addition of catecholase through 
green to black and after 5 minutes there is a definite black precipitate; 
saligenol is not changed by catecholase. 
Both oxydases together evidently form from saligenol, although 
more slowly, the same product as the catecholase forms from catechol. 
The most obvious hypothesis is therefore to assume that saligenolase 
forms catechol from saligenol. 
In any case this oxidation of saligenol (salicyl-alcohol) is quite 
different from that in the laboratory, where salicylic acid is always 
the final product a ). 
In the living plant this black substance *) never appears, but 
it only occurs, in necrobiosis; therefore the most attractive hypothesis 
seems to me that catecholase and catechol are separated from each 
other in the cells but that this is not so with saligenolase and 
saligenol, so that the latter enzyme can act and can form catechol, 
which then cannot be decomposed by catecholase, as is the case in 
necrobiosis and in the above mentioned experiments. 
In the former paper I investigated the changes of salicin and 
catechol in branches, with buds opening, when placed in water in 
the dark, and now I have done the same with branches budding 
while still attached to the plant. The objection in this case is, that 
the branches do not form a separate whole, so that influx and exit 
is possible, while assimilation very soon sets in. For all these reasons 
one may expect the observed values for the relation of the salicin 
disappeared to the catechol formed to differ more from those cal¬ 
culated by theory. I thus found, for instance, an increase of 94 mg. 
catechol accompanied by a decrease of 457 mg. salicin, i.e. a pro¬ 
portion of 21:100, while the molecular weights are in the proportion 
38:100. I also found however, that in the opening of the buds the 
amount of populin increases at the expense of salicin, so that the 
diminution in the glucoside which furnishes catechol on hydrolysis 
was placed at too high a value. 
I also repeated on a larger scale the earlier experiments with 
0 Neither catecholase nor saligenolase have any action on salicylic acid. 
2 ) Perhaps this black colouringmatter is the same as that formed from homo- 
gentisic acid under the influence of alkali. 
14 * 
