BARTHOLOMEW: HyALopsorA POLYPODII 197 
In studying stained sections of a very large number of sori 
which had not yet broken open, not one was found without a 
peridium. Fic. 1 shows a typical sorus just as it is breaking open. 
Ordinarily, though not always, by the time the sorus has become 
erumpent, the peridial cells have distintegrated to such an extent 
that they are scarcely noticeable. In the material which was dis- 
sected with needles the peridial cells could easily be distinguished. 
oS 
Fic. 2, Fragments of binucleate hyphae taken from the base of a sorus in which 
Most of the spores were thick-walled, X about 700. Camera lucida drawing. 
Perhaps the most interesting part of the results of this inves- 
tigation concerned the nuclear condition of the hyphae. The 
mats of mycelium which had been freed from the host tissues 
were transferred to separate slides and stained 11 toto. Without 
exception the cells of these hyphae were found to be binucleate. 
This was true of hyphae taken from the bases of sori in which the 
Majority of the spores were thick-walled, as well as of those taken 
from the bases of sori containing mostly thin-walled spores. 
Small fragments of the mycelium are shown in Fics. 2 and 3. 
Sectioned material shows the same facts as to the binucleate 
condition of the hyphae. 
From these observations it would seem that there can no 
* Infektionsversuche mit einigen Uredineen. Centralb. Bakt. Zweite Abt. 12: 
411-426. 1904; 16: 150-159. 1 
