Frey—Physiology of Venturia Inequalis. 
331 
figs. 16-20. The large cells of the ascogonium disappear gradually 
and lose their capacity to stain more densely than the surrounding 
hyphae. 
As previously stated, at the time of fertilization the trichogyne 
is non-septate. The ascogonium has no definite cell walls. It was 
impossible to find sufficient evidence to indicate whether or not 
rapid nuclear division occurred in the coil, but a large number 
of nuclei are found later, fig. 12, indicating that division occurs. 
The evidence points to migration of nuclei from the trichogyne as 
initiating the multinucleate condition. There was no nuclear di¬ 
vision apparent in any sections to indicate that the uninucleate 
cells of the ascogonium become multinucleate before fertilization. 
In the young trichogyne one can seldom find a nucleus. The as- 
cogonial coil contains several nuclei, fig. 10, but after the tri¬ 
chogyne has fused with the antheridial cells it contains many 
nuclei; often a chain of them may be observed in the trichogyne 
extending from the apical end to the margin of the perithecium 
or beyond, figs. 8-12. 
The nuclei of the ascogonium continue to grow in size until the 
cells no longer stain heavily, and there is apparent a great in¬ 
crease in the number of the cells. At this stage the perithecium is 
at its maximum size and it is difficult to make accurate observa¬ 
tions of the various stages of development. Sections cut in March 
from material gathered February 27 in the orchard have no heavy 
staining material left and the nuclei are not much larger than 
the nuclei of the vegetative cells. The contents of the nucleus 
which at first stained very deeply become more and more difficult 
to stain about the time of ascus formation, figs. 16, 21, 22. A cross 
section of the perithecium gives very little indication of differen¬ 
tiation in any of the tissues not arising from the coil. 
There is no evidence to indicate that typical ascogenous hyphae 
as described by Harper and Clausen occur. The whole content of 
the perithecium, with the exception of a layer of four or five cells 
at the periphery, seems to be occupied by asci and gelatinous ma¬ 
terial. All the large deeply staining cells of the ascogonium have 
disappeared, and the space formerly occupied by them is filled 
with asci which appear as if they originated from the basal por¬ 
tion of the perithecium, figs. 24 and 25ab. The only explanation 
formulated, and which agrees with the sections observed, is that 
apparently there is a breaking up and budding of the large cells 
of the ascogonium, forming a large number of small cells, the 
