184 BOTANICAL GAZETTE [MARCH 
spores copiously. Not only were the leaves badly infected, but 
also the petioles and the stem itself. 
These experiments, together with the production of the conidial 
stage on the leaves of the American elm inoculated with the 
ascospores of Gnomonia ulmea, prove conclusively that the two 
forms are merely stages of the same fungus. The enormous num- 
ber of spores produced by the conidial stage, as well as the fact 
that infection secured from inoculations with such spores was 
much more pronounced and occurred in a somewhat shorter period 
of time than from inoculation with ascospores, would seem to 
indicate that the Cloeosporium stage is the chief agency through 
which widespread dissemination occurs in the spring and early 
summer. 
Another Gloeosporium on elm 
While working with this fungus, a single tree in a nursery at 
Oconomowoc, Wisconsin, was found on which the leaf spots were 
quite different in external appearance from those on the surround- 
ing trees, most of which were abundantly spotted with the Gnomonia 
disease, although the trees were of the same species and had appar- 
ently been planted at the same time. Fig. 9 shows a leaf from 
this collection. The leaf spot is raised considerably more than is 
the case in the preceding species, giving the portion of the leaf on 
which it occurs a crumpled appearance where the spot becomes 
large, and is confined quite closely to the leaf veins, along which 
it spreads, often extending the entire distance from the midrib to 
the edge of the leaf, thus forming elongated streaks. The leaf 
veins also become browned for some distance beyond the spots, 
although the remainder of the leaf is a norma] green. The spots 
present a gray salt-and-pepper aspect, due to the whitened epider- 
mis over which the black conidial pustules are thickly scattered. 
The whitened appearance is due also to the disappearance of the 
contents of the epidermal cells and from the cells of the palisade 
layer immediately beneath them. This disappearance of cell con- 
tents is much more pronounced than in the Gnomonia ulmea spot. 
The acervuli are very numerous in a single spot and are quite 
commonly confluent. They are orbicular to oblong in shape, 
very irregular in outline, and are covered by the darkened cuticle 
