144 
William J. Hodgetts. 
seem to be ejected when the asci are observed in water appears to 
be due to the too great elongation of the inner ascus tube under 
these conditions, the internal pressure thus not rising to the extent 
required forcibly to eject the spores. In moist air the ascus tubes 
never emerge through the ostiole as far as they do when the 
perithecia are in water. 
In a damp atmosphere it was found that the spores could be 
thrown a horizontal distance of 0-4 to 2-0 cms. (usually about 1 cm.); 
and could be shot vertically to a height of 0-2 to 1*2 cms. above the 
ostiole. These distances are greatly exceeded by certain other 
Ascomycetes in which explosive discharge of the spores is known. 
De Bary 1 states that in the strongly puffing fungi, such as Peziza 
vesiculosa, P. acetabulum, Helvella crispa and Ascobolus furfuracens, 
the spores are thrown to a distance of more than 7 cms. ; in 
Sovdaria pmiseda they may travel 15 cms., and in the smaller 
species of this genus abont 2 cms.; in Rhytisma acerinum only a 
few mms. According to Buller 2 the spores of Peziza repanda are 
shot vertically a distance of 2 to 3 cms. above the hymenium, 
while those of Ascobolus immersus 3 are discharged vertically to 
a height of 25 cms., or even more, the maximum being 35 cms., 
while they could be shot horizontally 30 cms. The last example 
exhibits the greatest violence of spore-discharge known in any 
Ascomycete (although it is easily beaten by Pilobolus). These 
species discharge all the spores of the ascus similtaneously, the 
method commonly found in Discomyctes, but occurring also in 
some Pyrenomycetes ( e.g ., Sovdaria), and in Protomyces. 
Certain characteristic changes in the apical region of the 
ascus wall of Leptosphceria acuta can be traced during the matura¬ 
tion of the spores. The young ascus, filled only with granular 
protoplasm and oil-drops, shows at the extreme apex a circum¬ 
scribed thinner part of the inner coat of its wall (see Fig. 10), 
around which the latter is much thicker than elsewhere. The 
outer cuticular membrane can just be discerned, and appears to 
be uniformly thin over the apex of the ascus. When the spores are 
mature but the outer coat still intact the ascus is very turgid, and 
the inner coat appears thinner and uniform at the apex (Fig. 11), 
due no doubt to the fact that it is tightly compressed between the 
unyielding outer membrane and the turgid contents of the ascus. 
The two coats are now usually discernable only with difficulty 
(Fig. 11). Exactly what causes the inner coat to breakthrough 
1 “ Morph, and Biol, of the Fungi” Eng. Ed., 1887, p. 92, 
“ Researches on Fungi.” 1909, p. 236. 
Buller,” loc. cit., p. 252. 
