332 Wisconsin Academy of Sciences, Arts, and Letters. 
initial ascus cells arising from some of these cells. The ascogonium 
immediately after fertilization may contain seven or eight cells. 
Later stages show the contents staining less densely, vacuoles ap¬ 
pear and four nuclei are found in some cells. Distortion of all 
the cells is apparent and the inner contents of the perithecium are 
undoubtedly subjected to enormous pressure by the enveloping 
hyphae. By such intimate contact with the enveloping vegetative 
hyphae it is possible that the metamorphic tissue within receives 
nourishment. The cells of the enveloping tissue are uninucleate 
and are pressed into plates or rectangular polygons. At the time 
of fertilization they contain considerable food material but later 
this disappears. 
As the ascogenous cells decrease in size, or rather as they bud 
and new cells are formed, the cells so formed are uninucleate oi 
binueleate. It has not been possible to determine whether these 
cells form asci directly or by budding. The perithecium at this 
stage has reached its full size and it would be impossible for further 
budding and growth to take place unless some of the enveloping 
hyphae are absorbed, which seems, however, to occur at a later 
period. Possibly the cells elongate and by a process of rearrange¬ 
ment without much increase in the space occupied, the asci are 
finally developed to their full size. 
There is a considerable gap in my series of developmental ob¬ 
servations extending from the origin of the ascus to spore develop¬ 
ment. The ascus previous to the time the spores form is elongated 
and the nucleus or nuclei lie near the center, figs. 24-25. After 
the second nuclear division the ascus elongates still more and the 
nuclei migrate toward the periphery. About the time of the third 
division the ascus elongates again, the spores are delimited and the 
ascus is just wide enough at this time to hold the spore. Its length 
is approximately twice that of an ascus in the stage previous to the 
first division. 
The spores are arranged in a chain and fill the ascus with the 
exception of a portion at the base. Practically all of the proto¬ 
plasm of the ascus is exhausted, having been utilized in spore 
formation. A large number of cells forming the inner zone of the 
perithecium have been crowded aside, and their contents have dis¬ 
appeared. Many of the cells appear to be disintegrating. Three 
or four layers of heavy-walled cells constitute all that is left of 
the perithecium. Sometimes there is a cavity in the region below 
the ostiole as the perithecium elongates preparatory to discharg- 
