26 NortH AMERICAN SORDARIACEAE 
extreme difficulty that any of the old membranes can be found 
on opening the perithecium. Woronin * states that they are 
reabsorbed. Whether he ıs correct or whether the old membrane 
partially disintegrates and becomes pushed out by subsequent 
expanding asci does not appear clear to me. If the old ascus 
wall is observed in water outside of the perithecium it gradually 
disappears while one is studying it, and it is difficult even then to 
say what becomes of it. At any rate, it deliquesces in a very 
short time and this probably occurs in the perithecium as rapidly 
as in water outside of it. 
The same author also calls attention to the fact, which has 
been repeatedly although not constantly observed in the progress 
of my investigations, that the paraphyses are much more abundant 
in the old perithecia. It is well known that there is a considerable 
period during which the successive asci mature. Some are very 
young and probably contain but a single nucleus when others are 
mature. This is especially true in such forms as P. fimiseda which’ 
was the species especially studied by Woronin, as well as in 7. 
coproplula, P. zygospora, P. decipiens, and P. anserina. It does often 
appear that when the perithecium has nearly spent its force and 
contains but few asci, that the paraphyses are more numerous 
than in the earlier stages of development. It appears as though 
the paraphyses are developed as occasion demands and that when 
the perithecium ceases to produce new asci their place is occupied 
by new paraphyses which enable the few remaining asci to elon- 
gate and reach the ostiolum in a normal manner. It is evident 
that this would not be true in case the space was left vacant, for 
the asci would simply enlarge laterally as they often do when 
allowed to expand in water. In other words they would not be 
held by lateral pressure in such a way that they would be obliged 
to stretch in length more than in width. 
When the collector obtains a specimen of this group, it is of 
value to him if he has secured it at a time when the perithecia are 
full of asci. For then by rapid drying they are prevented from 
disseminating their spores. On the other hand the plants may be 
collected already dried suddenly in nature at a time and under 
such conditions that the spores could not be ejected. But it 
* Abhand. Senkenberg. naturforsch. Gesell. (Frankfort), 7: 339. 1869-1870. 
