20 NortH AMERICAN SORDARIACEAE 
found. But it is very difficult.to demonstrate the actual fusion of 
elements. One point regarding the development of the perithe- 
cium has been very interesting. It may be a matter of common 
observation, but it has not been discussed, at least to any great 
extent. The perithecium which originates from a few erect coiled 
branches of mycelium early becomes a closed globular conceptacle 
with neither beak nor ostiolum. (S. fimicola.) The beak is de- 
veloped later by a process of unequal growth, as it were, at the 
apex of the globular perithecium and finally the thin wall is 
broken, forming the ostiolum. The latter process is beautifully 
illustrated in Sporormia minima. If the perithecia of this species 
in various stages of development are carefully isolated from the 
substratum, some of them will be found with short delicate light- 
colored papilliform beaks, but with no ostiolum whatever. In 
two cases I have seen the membrane over the ostiolum actually 
ruptured by an expanding ascus membrane. Of course it is un- 
derstood that the hyphae of which the perithecia are formed do 
not entirely lose their identity in many species. As has been 
pointed out by Woronin they may often be traced through the 
beak especially, and often appear to be continuous with the short 
paraphyses which fill the narrow channel leading to the ostiolum. 
In Sporormia minima the wall of the perithecium is at most three 
or four cells in thickness and the continuity of the hyphae is en- 
tirely lost, while in Pleurage fimiseda there occurs a wall which 
consists of as many as ten or twelve cells in thickness and is differ- 
entiated into three distinct layers. 
In spore development, the greatest interest attaches to the 
genus Pleurage on account of the peculiar appendaged condition of 
the spores. No effort will be made here to go into the cytolog- 
ical aspect of this subject for the perusal of which the reader is 
referred especially to the works of Harper* and Dangeard + on 
closely related forms. 
In all species of this genus wherein primary appendages occur 
the spore goes through a most peculiar set of transformations : 
at first it is a short cylindrical hyaline straight or curved cell 
whose contents do not differ materially from that of the ascus in 
* Jahrbücher wiss. Bot. 30 : 249. 1896. Annals Bot. 13 : 507. 1899. 
T Le Botanist, 5: 245. 1897 
