64 Von SCHRENK: TEACHING OF VEGETABLE PATHOLOGY. 
the bark of trees, have a decided interest for him, and ought to be 
alluded to at least in any course of vegetable pathology. 
A third phase which I wish to touch upon briefly deals with 
the influence of environment on the disease-causing factors, partic- 
ularly the fungi. Many spores of fungi must undergo resting periods 
of various lengths of time before germinating ; others do not ripen 
until late in the winter. Sclerotia must undergo freezing or a rest- 
ing period. I believe truly that there are many of us that know 
positively that the ascospores of Jicrosphacra germinate some- 
times and produce patches of mycelium, and that the sclerotia of 
Claviceps form perithecia bearing heads, but how many of us have 
ever seen these spores germinating, or tested the length of time 
necessary to do so? We have built a ‘resting frame”’ so-called 
for our fungus friends in the Missouri Botanical Garden, where 
they lie under leaves, and are disturbed every once in a while, 
and put under conditions where they might change, side by side 
with spores or sclerotia kept indoors all the time, Sometimes — 
our spores germinate and sometimes they never do. But eve? 
then the student learns the lesson that the spores of fungi have 
adapted themselves to the peculiar conditions of environment, | 
and, will respond only when these are exactly right. Under 4 
proper conditions most spores will germinate, and it is a far more | 
instructive lesson to have them do so after repeated failure than a 
give up the first time. I have always remembered the sad face 4 
and drawl of the man in my class at college who said that it wa q 
all very nice to study the sections of cluster cups and see mounts 
of germinating teleutospores and sporidia, but he didn’t think they 
ever did those things outside, if so, why didn’t we ever sce them 
Therapy, or healing, forms a small part of our study, for with 
plants the maxim that prevention is better than cure must always 
hold true. Spraying and other fungicidal methods may pr operly 
be experimented with on a small scale, but only with infected 
plants. With smuts the various seed treatments can be carried 
out without much trouble, at the same time that smut-infected 
seeds are planted. 
Summing up briefly, I would emphasize the fact that in all the 
phases of this study the living plant must be kept in, the fore 
ground. It goes withcut saying that the division suggested above 
