Wormald. — ‘ Brown Rot ’ Diseases of Fruit Trees . //. 147 
Botrytis cinerea when growing on grapes and on sterilized wine ‘ must 
This enzyme, however, is described as oxydizing hydroquinone, while in 
repeated experiments with the oxidizing enzyme of Monilia cinerea no 
action on hydroquinone could be detected. 
Martinand found that oenoxydase is destroyed by heating to 72 0 C. 
and keeping it at that temperature for four minutes. The Monilia enzyme 
also loses its power of oxidation when similarly heated. In most of the 
experiments described below the control tubes were heated for two minutes 
in a water-bath at ioo° C. In one experiment, however, the temperature of 
the bath was 72 0 C. 5 when the tubes were plunged in and kept at that 
temperature for four minutes ; on cooling the tubes and applying the 
guaiacum test no reaction occurred, while in corresponding unheated tubes 
a vigorous reaction was soon evident. 
The action of the enzyme tannase (secreted by Aspergillus niger and 
Penicillium spp.), which has been investigated by Fernbach (10), Pottevin 
( 22 ), and Knudson ( 13 ), is one of hydrolysis, tannic acid being hydro- 
lysed to gallic acid. The enzyme secreted by Monilia cinerea is therefore 
quite different from tannase, and is probably more nearly related to the 
oxidase found by Thatcher ( 25 ) in apples and that described by Crocker 
and Harrington ( 7 ) as occurring in the ‘ seeds’ of certain grasses. 
The experiments just described suggested the procedure finally adopted 
in investigating the oxidizing activities of the strains of Monilia which had 
been isolated and cultivated, a comparative study of those strains which had 
been used in the inoculation experiments on apple flowers carried out in 
1918 being particularly desirable. The general method employed in this 
series of experiments was one which eliminated as far as possible differences 
due to variations in environmental factors and in manipulation. Thus 
throughout the series the following points were observed : 
1. The same nutrient medium was used for all the experiments with 
the exception of Expt. 8. 
2. The cultures to be tested were started from vigorously growing 
mycelium taken from the edge of young agar cultures. 
3. The cultures were grown in Petri dishes 8-5 cm. in diameter 
(internally) and 20 c.c. of the culture liquid were used in each. 
4. The cultures were incubated at 25 0 C. for seven days, the oxidase 
test being applied on the seventh day. 
The culture medium was an extract of dried peaches. The apple 
extract used in previous experiments was rejected because of the coagula- 
tion of the pectin under the action of the fungi, the coagulum rendering the 
pipetting of small quantities of the liquid troublesome and inaccurate. 
Uschinsky’s solution and a synthetic medium which Coons (6) found to be 
suitable for Plenodomus fuscomaculans both gave far less vigorous growth 
than fruit extracts in the case of the Monilias. Prunes, which had been 
