1921] MILES—LEAF SPOTS OF ELM 193 
4. An interascicular pseudoparenchyma is found present in the 
perithecium almost until the period of maturity. 
5. In the process of ascospore expulsion an entire ascus enters 
the lower part of the ostiolar canal, and the eight spores are appar- 
ently discharged simultaneously. 
6. The ascospores could not be made to germinate either in 
tap or distilled water, in nutrient solutions, on solid media, or on 
the living leaves of the English or Scotch elm. They germinated 
readily on the leaves of the American elm, however, thus indicat- 
ing that they require a special stimulus of some sort which is 
present in the leaves of some species of U/mus, but absent in 
others. 
7. The fungus matures most rapidly during the winter on 
leaves which are neither too exposed nor in too damp a situation. 
When immersed in water or in intimate contact with the soil, the 
fungus dies, and only the empty husks of the perithecia remain. 
8. A conidial stage was found constantly associated with this 
ascigerous form. It is described as a new species, Gloeosporium 
meum. 
9. The connection between the two forms was conclusively 
proven by inoculations. The ascospores of Gnomonia ulmea gave 
rise to spots on the leaves of Ulmus americana which were entirely 
typical of Gnomonia, and which bore the acervuli of Gloeosporium 
ulmeum. The spores of this form also readily infected the leaves 
of the American elm, and appeared even more virulent than were 
the ascospores, indicating that this form is probably the agent by 
which extensive dissemination of the fungus is wiccien be in spring 
and early summer. 
10. A new leaf spot of the American elm, caused by Cloeo- 
sporium ulmicolum, another new species, is described. This 
species differs from the one previously described in the characters 
of the spot and in the larger size of the spores. 
11. Systremma Ulmi (Schleich.) Thiess. and Syd. causes a leaf 
spot of the European elms in Europe. Gnomonia ulmea has been 
very much confused with this fungus, and as a consequence has 
gotten into the literature as occurring in this country. The 
probability is, however, that it does not occur in America at all. 
