170 ‘* BOTANICAL GAZETTE [MARCH 
FURTHER DEVELOPMENT OF PERITHECIUM 
In the further development of the young perithecium all sign 
of the connection with the subcutaneous stroma soon disappears, 
as is shown in fig. 2, which is a slightly older stage. The structure 
has increased in size, chiefly by the enlargement of the portion 
which is later to become the perithecial cavity, but which is now 
filled with a dense pseudoparenchyma. The wall has also increased 
somewhat in thickness by the formation of new layers on the 
inside. As yet there is no sign of a beak or ostiole, although the 
wall cells on the lower side of the perithecium, opposite the stroma, 
are somewhat denser in protoplasmic contents, as is shown by the 
slightly darker color. Fig. 8 shows a still later stage of develop- 
ment in which the perithecium has practically doubled in size, 
since the two figures are of the same degree of enlargement. The 
central area has enlarged and the wall become still thicker. The 
darkly stained portion is composed of young ‘asci which are not 
yet clearly differentiated. On account of the nature of the material, 
the leaves showing this stage of development having first been 
collected and dried and later softened with lactophenol, as well as 
on account of the very small size of the nuclei, the cytological and 
other minute details of this development could not be accurately 
determined. The main portion of the perithecial cavity is entirely 
filled with a very fine pseudoparenchymatous material, which 
when crushed or teased out appears merely granular in structure, 
with some slight evidence of anastomosing hyphae. In the origi- 
nal description of the fungus, SCHWEINITz mentions the granular 
nature of the perithecial contents. The beak or rostrum and the 
ostiole are here seen in the earliest stages of their development. 
The same group of more deeply staining wall cells, mentioned in 
connection with fig. 2, is still evident, but has increased in size to 
form a sort of plug of tissue, which by its growth forces the outer 
layers of the perithecial wall outward and downward on the lower 
side to form the outer wall of the beak. As the multiplication of 
these actively dividing cells continues, their long axis changes 
from horizontal, as at first, to a direction parallel to that in which 
the beak is being developed. The cells nearest the center of this 
elongating beak separate in their continued growth, leaving 4 
