1895.] Development of Uncinula. 489 
studied the peritheci d to be flattened on one side, the flat- 
tening sometimes amounting to a concavity. In such cases the 
asci were compressed vertically and considerably distorted. 
Doubtless part of the flattening was due to the shrinkage of 
the tissues during imbedding, but some of it was normal. 
One of the principal objects of these studies was to follow 
the development of the fungus during the winter and to de- 
termine if possible when and how the ascospores germinated 
and the manner in which the host was infected in spring. It 
was deemed especially desirable to germinate the ascospores, 
as the evidence as to how this takes place in the Erysiphee is 
comparatively meager. Leaves of both ampelopsis and vitis 
containing the perithecia of the uncinula were collected in the 
autumn and stored in several ways. Some were placed on 
the ground and covered with stones and boards, while others 
were tied up in cheese cloth sacks and the sacks were then 
thrown on the ground out of doors and tied to stakes in order 
to prevent them from blowing away. This last method was 
found to be most satisfactory, as when the leaves were cov- 
ered with boards they rotted so badly that most of the peri- 
thecia were lost. Frequent examinations were made of de- 
bris under vines which had been attacked by the uncinula the 
previous summer. No material of value, however, was ob- 
tained in this way, all traces of perithecia disappearing early 
in December. 
The first change of importance in the perithecia was the 
disappearance of the appendages. After December Ist it 
was rare to find a perithecium with all of its appendages in- 
tact. The hooked ends are usually the first to break off and 
soon the entire appendage disappears. The asci and spores 
The perithecia were from time to time removed from the 
leaves which had been exposed to the weather and placed in 
Van Tieghem cells, in the bottom of which was a drop of 
sterile water. Under these conditions the perithecia were 
kept properly moistened and could be examined with the 
Microscope at any time. Perithecia collected after January Ist 
34—Vol. XX.—No. II. 
