22 Proceedings 
noticed on many wild plants, e.g. on Burdock, Polygonum 
aviculare, Heracleum Sphondylium, Meadow Sweet, Willow 
Herbs, Plaintain, &c. 
Such are the characteristics and the life history, so far 
as it is known, of the Zrysiphacee. Now I want to point 
out that in connection with this group of fungi there exist 
three problems—solutions to which could, I believe, be 
furnished by patient field work. These problems are not 
only of great scientific interest, but one of them is of very 
considerable economic importance. ‘These problems may 
be presented in the form of three questions :— 
First. How do the ascospores infect plants ? 
Now in books it is stated that the ascospores are in- 
capable of germination when produced in the autumn, 
but “in the Spring germinate and infect fresh host-plants.” 
This bald statement—“‘in the Spring the ascospores germ- 
inate and infect fresh host-plants,” is all that one finds on 
the subject ; and, when one enquires for details, it is found 
that this vague statement even rests on assumption. No 
details are forthcoming of the process as it must take place 
in Nature. We must remember that these perithecia are 
produced on the leaves of deciduous plants; in the autumn 
the leaves bearing the perithecia fall with the rest, and rot 
on the ground. How do the ascospores then find their way 
in the spring to fresh hosts? Inthe case of the species 
Phyllactinia corylea, which grows on trees—such as the oak, 
ash, beech, &c.—how do the ascospores get from the ground 
to the top of such tall trees ? 
Keeping to stern facts of observation, we have only 
one little piece of fragmentary knowledge on the subject. 
In 1874, Wolf,a German botanist, succeeded in germinating 
in a drop of water the ascospores of the Grass Mildew. 
These germinating ascospores when placed on a leaf 
of grass penetrated the cuticle and formed haustoria. 
This is the single positive result obtained up to the present 
on the subject of infection by ascospores. 
Of course, theories rush in. One mycologist has stated 
his belief that the ascospores germinate in the humus of 
the soil, and there produce myriads of very minute, yeast- 
iene 
