500 
F. D. HEALD AND R. C. WALTON 
ascus occurs in nearly all species of this class. The forcible expulsion 
of spores from perithecia was not observed however until a later time. 
Several of the noteworthy observations may be mentioned. Tulasne 
(20) observed the ejection of the spores from the perithecia of Claviceps 
in 1861 ; this was confirmed by De Bary (6) and the same phenomena 
noted for Cordyceps. The details of the process of spore expulsion 
were studied by Pringsheim (13) for Sphaeria scirpi in 1858; by 
Woronin (24) for Sphaeria lemaneae in 1869; by Wolff (23) for Erysiphe 
in 1875; by Zopf (25) for Sordaria species in 1880; while De Bary in 
1884, in his discussion of the expulsion of spores, claims that the proc- 
ess is common in the Pyrenomycetes. It may be pointed out in this 
connection that ascospores are not infrequently set free from the 
perithecium by the mucilaginous swelling of the asci and are forced 
out embedded in mucilage in drop-like aggregations or in the forms 
of tendrils or spore-horns instead of being set free by the explosion of 
the asci. Pyrenomycetes showing the two types of spore expulsion 
have been designated as active and inactive. In the active forms, 
according to De Bary, the entire spore content of the ascus may be 
ejected simultaneously as first described by Zopf (25) for Sordaria, or 
the spores may be expelled in succession as was first shown by Pring- 
sheim (13) for Sphaeria scirpi. In connection with this claim the 
more recent view of Falck (8) should be presented: "According to 
my investigations conducted on species from all classes, I can state it 
as a rule that in all active Ascomycetes the spores are shot out singly, 
that is, one spore after the other at regular intervals. The intervals 
are mostly so short that the ejection appears to the eye as single. In 
proper microscopic preparations in which the ejection is often retarded, 
one can follow directly how one spore after the other is emptied from 
the ascus," 
According to all published observations, to be referred to later, 
the expulsion of the spores from the ascus in Endothia is simultaneous. 
The forcible expulsion of the ascospores of the black rot fungus, 
Guignardia bidwellii, was noted by Scribner and Viala (18) and the 
following main facts established : 
I. The ascus swells up to double length and is set free from the 
perithecium through the ostiole or by the rupture of the wall. 2. 
When the asci have escaped they expel the contained spores one at a 
time. 3. The maximum height of projection was 4 cm. 4. A tem- 
perature of 20°-30° C. was necessary for expulsion. 
