Pammel — Sclerotinia Libertiana. 195 
light, and in a single day showed strong heliotropic curvature. 
In two or at most three days they had bent sharply upon them- 
selves, and were again directing their tips obliquely towards 
the light in response to the combined influence of negative 
geotropism and positive heliotropism.’’ 
The tip began to increase in size, in eight days the stalks be- 
gan to enlarge very decidedly at the tip; during the early stage 
it consisted of a slender thread with a small depression at the 
upperend. As the depression became larger the end was more 
or less flattened and after it had attained full size the whole 
fell and rapidly disappeared. A cross section through one of 
the cups shows a very large number of asci, each of which con- 
tains eight ascospores. Between the asci are innumerable fine 
threads, the septate paraphyses. The ascospores germinate 
in a short time. The exact time was not noted, but Wakker ! 
observed that germination in Sclerotinia tuberosa occurred in 
24 hours. 
The germ tube bears sporidia which are entirely functionless. 
Wakker in studying the different Sclerotinias finds that 
in the hyacinth disease the sclerotinia cup rarely develops, 
which leads him to believe that Sclerotinia tuberosa is the truly 
indigenous species of Europe and that Sclerotinia libertiana 
and S. bulborum are derivatives, but under certain conditions 
have become somewhat changed. 
EXPLANATION OF PLATES. 
PraTE I. 
1. Sunflower root showing sclerotia forming. 
2. Sclerotinia libertiana, Fuckl. Stalk apatites. hyphae springing from the 
main stalk in the form of fine thre — magnifie ed about fifteen times. 
3. Celis of the stalk more magnified. 
4. Hyphae from sunflower root before the formation of sclerotia, magnified 
500, 
PuiaTE II. 
5. Hyphae from the same source but branched, magnified 500. 
: Sclerotium with fruiting body, twice enlarged. 
- Sclerotium with fruiting body, earlier stage 2. 
. Asci and ascospores, magnified 350. 
9. Cross section of sclerotium: rind shown at a; at}, interior white portion, 
magnified 500. 
1 Le. 
