MORPHOLOGY AND LIFE HISTORY OF SOME ASCOMYCETES 44I 
winter, before the end of December. They then seem to pass through 
a necessary resting stage. All attempts to hasten the maturity of the 
perithecia and the formation of ascospores by placing the leaves bearing 
them in a moist chamber in the laboratory at this period have resulted in 
failure; although, after about the first of February, mature ascospores may 
be obtained by this same method in from one to four days. 
The nuclear divisions in the ascus have not been studied carefully. 
They seem to occur at irregular intervals during the spring and winter. 
This irregularity, together with the difficulty of proper killing and fixing 
of material, makes such a study very tedious. The colorless pseudoparen- 
chyma in the interior of the perithecium is of such a nature as to prevent 
penetration of Flemming's solution and other killing agents of the chromic 
acid group, which give very good results at all other stages. The only 
solution which has proved at all satisfactory is one made by dissolving 
I J grams of picric acid in 100 cc. of 70 percent alcohol and then conducting 
into this solution the fumes from i gram of NaSOs treated with a few cubic 
centimeters of sulphuric acid. After these colorless cells had been crushed 
by the growth of the asci, that is, when the asci were nearly mature, Flem- 
ming's solution gave excellent preparations. Asci containing four nuclei 
have been found during January, and by the first of March the young asco- 
spores are beginning to form ; but the spores do not mature until the early 
part of May. 
The spores are imperfectly biseriate in the ascus. They are at first con- 
tinuous; but when mature they are septate, each spore being constricted 
into two slightly unequal cells. The smaller cell, toward the base of the 
ascus, is pointed at the end; the other cell is thicker and rounded at the 
apex. The ascus is slightly thickened at the apex but does not open by a 
pore. 
The maturity of the perithecia is remarkably uniform. Spore discharge 
continues during only a few days, if the leaves remain damp. 
The ascospores are apparently the only means by which the fungus is 
carried through the winter and are probably responsible for all spring 
infection of the host plant. No conidia of any sort have ever been found 
during the winter and spring. The conidiophores appear to be dead soon 
after the leaves fall. The first spots begin to appear on the older leaves 
of the host about a month after the ascospores mature. 
Genetic Relationship of the Spore Forms. The relation of the spermogonia 
and of the perithecia to the Cercospora stage is shown by their development 
at the base of, and direct connection with, the conidiophores. Very often 
remnants of these old conidiophores may be seen on the perithecial walls 
when the ascospores are mature in the spring. Frequently also a spermo- 
gonium and a perithecium develop side by side with a single wall between 
the two cavities (see fig. 8) . This observed connection was also corroborated 
for the conidial and ascigerous stages by comparison in cultures and by 
inoculations. All attempts to germinate the spermatia failed. 
