Ascigerous Stage of a ‘ Brown Rot J Fungus . 129 
Dimensions of the Ascospores. 
Apothecium. 
Number of 
spores 'measured . 
Range of variation. 
Average size. 
No 1 
100 
11. 0-18 x 5.0-7 
13.6 X 6-1 
2 
100 
8 - 5-17 x 4 - 5 - 8 
12.2 x 6.0 
3 
100 
9.5-19 x 4.5-8 
12.3x6.3 
4 
100 
7.0-19x4.5-8.5 
1 1.9 x 6.3 
Result 
400 
7.0-19x4.5-8-5 
12.5 X 6.2 
Cultural and Inoculation Experiments. 
The ascospores germinated readily in distilled water and on prune- 
agar, and germ-tubes up to 250 /x in length developed within twenty-four 
hours at room temperature (i8°-2o° C.) ; the germ-tubes produced in distilled 
water were about 3 /x in diameter, and few produced branches during the 
first twenty-four hours (Fig. 8), while on agar the germ-tubes were 6-7 /x in 
diameter, and many were branched (Fig. 9). At the end of forty-eight 
hours the germ-tubes had produced numerous branches, and those growing 
on the agar had, in some instances, grown to a length of 2 mm. 
Cultures were obtained by isolating ascospores on prune-agar plates 
and transferring the uncontaminated sporelings to other plates when two 
days old ; in this way pure line strains were obtained, each derived from a 
single ascospore. These cultures on prune-agar plates showed the zoned 
and lobed growth (characteristic of strains of Monilia cinerea , Bon., obtained 
from plums, cherries, and peach twigs in this country) which distinguish it 
from the American Sclerotinia. 
On transferring a little of the mycelium from the plate cultures to 
sterilized potato in test-tubes, white hyphae grew out at first, but within five 
days, at room temperature, grey tufts of conidiophores bearing chains of 
conidia of the Monilia cinerea type developed. 100 conidia from each 
of three such cultures on potato, eight days old, were measured, and the 
following measurements obtained : 
(1) 9-0 x 6-24-0 x 15-5 ju, Average 1 6-4 x n*9 /x 
(2) 9*5 x 7-24*5 x 18-5 fx „ i5‘9 x n*9 ^ 
(3) 9-ox 8-23*5 x 17*5// „ 15-2x11 -5/x 
These results are similar to those given by strains derived from conidia 
taken from plums naturally infected with Monilia cinerea ; thus for seven 
such strains, when cultivated on steamed potato, and the average dimen- 
sions of 100 conidia produced on the medium determined for each, the 
averages varied from 15-5 x 11-5 /x to 16-0 x 12*5 /x and 17-0 x 12*0 /x. 1 
In order to confirm the evidence supplied by the cultural studies that 
the Sclerotinia and the grey Monilia found on plums and cherries are forms 
1 See Annals of Appl. Biol., vol. iii, p. i 79. 
K 
