158 
BASGOMBE BRITT HIGGINS 
In the leaves of P. serotina, P. virginiana and P. mahaleb the stroma 
never becomes black but changes to a yellowish brown or to a dull 
orange color with a waxy appearance when wet. The paraphyses 
are differentiated much earlier (in January or February) and the 
ascospores mature slightly earlier. Leaves of P. serotina received 
from Clemson College, S. C, on March 13, bore mature fruit bodies. 
In leaves from the same tree received in the fall and wintered over in 
wire cages (Ithaca), they did not mature until about a month later. 
On the plum (P. insititia and P. domestica) the stromata often 
turn coal black before the leaves fall. They protrude from the 
under surface of the leaf and because of the black color are very 
prominent all during the winter. The spring development is much 
slower and later than in P. virginiana, and slightly later than in P. 
avium. In all other respects the general development as far as observed 
was similar to that described on P. avium. 
Infected leaves of all the host species were brought into the labora- 
tory at intervals during the fall and winter. For some reason, how- 
ever, the fruit bodies refused to develop if brought in before the para- 
physes had been differentiated. Perhaps the excessive moisture, or 
else lack of freezing, prevented the formation of the ascogenous hyphae. 
It was also noticed that the fruit bodies failed to develop outside when 
the leaves were packed closely together and therefore moist and poorly 
aerated, and also when a leaf was folded so that half of its under surface 
was next the ground the fruit bodies failed to develop on the side in 
contact with the ground. 
When plum leaves were kept very moist in a closed moist chamber 
the asci did not develop, but conidia were formed instead. This 
may have been due to the inherent nature of the fruit body, but that 
it was due to the effect of excessive moisture is more probable. Leaves 
which had been kept very wet until most of the fruit bodies had 
developed into conidia-bearing structures, were gradually dried by 
exposing to the air for a few minutes each day when normal asci and 
paraphyses developed. 
Relation of the Ascigerous Stage to Cylindrosporium 
In order to remove all doubt as to the genetic connection between 
this ascogenous fungus and the Cylindrosporium which is parasitic 
on the several host species, several series of inoculations and cross 
