confluens and the Morphology of the Ascocarp . 369 
genous hyphae and paraphyses from any one oogonium and 
its stalk is always to one side of the oogonium and never 
about it as a centre. As noted above, the several oogonia 
of a cluster always develop their branches on their adjacent 
sides as far as possible so that the centre of development 
of the apothecium is the centre of the cluster of reproductive 
organs. In this way symmetrical circular apothecia are 
developed similar in appearance in ail respects to the fruit- 
body of Ascobolus , which develops from a single ascogonium. 
Such irregular masses, as are shown in Fig. 98 of De Bary’s 
text-book ( 13 ), I have never found arising from a single 
rosette, but by fusion of the fruit-bodies from a series of 
rosettes crusts can be formed of considerable size and 
extremely irregular outline. 
When, as I have noted above, a single pair of sexual cells 
develops a fruit-body, it is always unsymmetrically placed 
with reference to the oogonium which lies exposed on one 
side of the hypothecium. This shows that the development 
of the ascogenous hyphae and paraphyses chiefly on one 
side of the oogonium is not merely a correlation of the 
formation of the compound fruit-body. The true explanation 
is probably that the oogonium is too large relatively to the 
size of the entire fruit to be properly enclosed by the hypo¬ 
thecium without distortion of the hymenium and the formation 
of a poorly developed point in its centre. Hence the 
oogonium is left at one side, and its branches with the 
vegetative hyphae develop a symmetrical, somewhat top¬ 
shaped apothecium. 
Pyronema belongs to that group of the Discomycetes in 
which the hymenium has no peridium or lateral boundary 
of vegetative protective hyphal tissue around the hymenium. 
This condition is very well shown in sections (Figs. 20, 23), 
the paraphyses being seen to form the outermost boundary 
of the hymenium on its entire periphery. This character in 
Pyronema is probably correlated with the habit of producing 
compound apothecia and still larger crusts by fusion. It 
would be plainly a waste of material to attempt to delimit 
