3 1 6 Wormald. — Further Studies of the Frown Rot'' Fungi. I. 
IV. Comparative Tests for Presence of Oxidase 
in Cultures. 
In a previous paper 1 it has been shown that two forms of Monilia 
cinerea , referred to as forma mali and forma pruni , are distinguishable not 
only by a difference in the degree of parasitism shown by the two forms 
when apple flowers are inoculated with their conidia, but also by a difference 
in the rate of secretion of an oxidase when the fungi are grown in liquid 
culture media. In that article the method adopted in applying the test for 
the presence of oxidase is given in detail ; 2 the tests as applied to the 
Shoot-Wilt fungus were carried out as described there, except that another 
culture medium was used (viz. a 2 per cent, extract of prunes) and, the 
thermostat not being available, the cultures were grown, and the tests 
carried out, in a warm room at a temperature of about 20° C. instead of at 
25 0 C. as in the previous experiment. 
In the present instance two isolations of the Shoot- Wilt fungus were 
used, and, for comparison, a culture of Sclerotinia cinerea originally started 
from an ascospore, and two cultures of Monilia cinerea f. mali from apple 
trees, were tested simultaneously. For convenience these may be indicated 
by the letters A, B, C, D, and E, as follows : 
A. Shoot-Wilt Monilia , Isol. I : from the mycelium of a Shoots 
Wilt canker. 
B. Shoot-Wilt Monilia , Isol. Ill: isolation from a conidium of 
a fructification on a Shoot-Wilt canker. 
C. Sclerotinia cinerea , Isol. I : from an ascospore of an apothecium 
found on a mummied plum. 
D. Monilia cinerea f. mali, Isol. XXIII : from a conidium of 
a Brown Rot canker on an apple tree (Kent). 
E. Mojiilia cinerea f. mali. Isol. XXIV : from the mycelium in 
a dead spur of an apple tree (Ross-shire). 
B and E were the fungi used in the experiments described under ‘ Inocula- 
tion of Apple Flowers ’ ; E produced typical Apple Blossom-Wilt, while B 
failed to do so. 
Two plate cultures of each were started, and when they were ten days 
old five of them (viz. one of each isolation) were tested for oxidase, guaiacum 
and pyrogallic acid (2 per cent, solution) being the reagents used. By the 
tenth day the mycelium of D and E was much darker than that of A$B, 
and C. The liquid was strained off from the mycelium, the former only 
being used in the tests. 
D and E readily gave the oxidase reaction, a blue colour being evident 
in the guaiacum tubes within half an hour ; the colour developed into 
1 Wormald, H. : The ‘Brown Rot’ Diseases of Fruit Trees. II. Ann. Bot., xxxiv, 1920, 
pp. 1 43-7 L 
2 loc. cit., pp. 147-50. 
