133 
A scigerous Stage of a ‘ Brown Rot ' Fungus. 
sets of dimensions are practically included in those given by the asci with 
monostichous spores of the Sclerotinia found on plums. The spores of 
S . laxa are described as ‘ fere semper monostichis, raro subirregulariter 
dispositis, utrinque obtusissimis, saepe 2-3 guttulatis ’ ; this general 
description of the spores conforms to Westerdijk’s description and figures 
of the asci and spores of the cherry Sclerotinia. In neither case are asci 
with distichous spores mentioned, but as this is a condition which obtains 
only when the apothecia are quite ripe and liberating (or just about to 
liberate) spores, it might not have come under observation where suitable 
material was very limited. 1 
The sclerotia from which Sclerotinia laxa developed were thicker 
(1 mm.) than those of the plum Sclerotinia (0*3-0 -5 mm.), but this variation 
is probably merely due to a difference in the texture or size of the fruits. 
Aderhold and Ruhland obtained cultures from the ascospores of the 
apricot Sclerotinia and reproduced the conidial stage ; this they describe as 
appearing, to the naked eye, similar to Monilia cinerea ; they found, how- 
ever, that the conidia of the former were larger than those of the latter. 
Thus the dimensions of the conidia of M. laxa are given as 12*4-23*8 x 
9*3 -I 5*5 M with an average of i(5*i x io*8 g, those of M. cinerea as 9*3- 
14-5 x 6-2-12-4, the average size being 13-8x9.9 5 /a. It will be seen 
from the inoculation experiments described in this paper that the 
dimensions obtained for the conidia of the plum Sclerotinia when growing 
on plums and cherries were in fact rather higher than those quoted for 
Monilia laxa. 
Having regard to these facts, it would appear, therefore, that the 
Sclerotinias recorded for Europe as occurring on apricots, cherries, and 
plums show no essential morphological differences. To determine whether 
they are to be distinguished culturally, or biologically, with respect to their 
host plants will require further study. Aderhold and Ruhland suggest that 
there is a feeble specialization of parasitism, and that 5 . laxa is more or less 
confined to the apricot. Thus they had observed on one occasion that 
apricots were found severely attacked by Brown Rot, while neighbouring 
peaches and cherries were free from the disease ; again, from their inoculation 
experiments, although they were able, with S. laxa , to infect the flowers not 
only of apricots but also of cherries, plums, and apples, they found that 
£ gegeniiber Sclerotinia laxa die Pflaumenbliiten sich relativ resistent erwie- 
sen \ Though this evidence is suggestive it is not conclusive, and positive 
proof can only be obtained by parallel series of inoculations with strains of 
Sclerotinia from the various hosts. 
1 Aderhold and Ruhland appear to have obtained but one fully developed apothecium on 
apricots; they write, ‘Von den beiden am 1. Mai F ruchtkorper zeigenden Aprikosen-Mumien trug 
die eineein wohlentwickeltes und ein kleineres Apothecium, die andern 3 unvollkommen ausgebildete 
Apothecien 
