360 Harper.—Sexual Reproduction in Pyronema 
nuclei. The chromatin is also sharply differentiated in the 
form of strands or granules on the inner surface of the nuclear 
membrane, or distributed in the nuclear cavity (Figs. 17-20). 
The ascogenous hyphae continue their growth and the 
ascogonium is rapidly emptied of its nuclei and protoplasm 
(Fig. 19). These ascogenous hyphae are extremely crooked 
and soon become septate. At first they may grow downward 
as it were to meet the developing vegetative hyphae among 
which they wind about in the most intricate fashion, as is 
only partly shown in Fig. 39. This preliminary downward 
growth would seem to indicate that in some degree the 
ascogenous hyphae anticipate in their development the vege¬ 
tative paraphyses with which they are to be associated. It 
is probably true that the greater ease with which the asco¬ 
genous hyphae can push in among the vegetative hyphae at 
this early stage, more than compensates for any loss resulting 
from the detour they make in turning downward at first 
instead of growing directly upward toward the position of the 
future hymenium. 
After the ascogenous and vegetative hyphae have become 
thoroughly interwoven, a rapid stretching upward of the 
whole mass ensues. In this growth the vegetative hyphae 
outstrip the reproductive ones and form at first a cone-shaped 
mass made up of their elongated slender, densely aggregated 
tips. These elongated upper extremities of the vegetative 
hyphae of the envelope are the young paraphyses. Their 
number is being constantly increased by the pushing in of 
new branches from below, and thus the cone-shaped outline 
is maintained. The ascogenous hyphae grow upward for 
a certain distance in company with the vegetative hyphae. 
Their growth upward then ceases and they spread out 
horizontally, forming a rather dense layer at the base of the 
cone of paraphyses which may be called, if we restrict the 
term somewhat from its usual significance, the sub-hymenial 
layer. This interwoven horizontal layer marks the base of 
the hymenium. It is a little below the level of the point of 
union of the conjugating tube and antheridium (Fig. 20). 
