New YorK AGRICULTURAL EXPERIMENT STATION. 281 
Whether the type of spores produced by the members of the 
teleutosporic and ascosporic groups may be controlled by either 
or both of the above methods is yet an open question. In case 
of the Mycospheerella-wilt fungus, on its normal hosts, the 
environment seems the important factor. The cortical tissues 
have been thoroughly permeated by the mycelium and killed 
when the pycnidia are produced; and generally these tissues 
are comparatively dry before the perithecia appear. Some of 
the latter conditions are found on the dead pumpkin-vine 
slivers, though others are absent. In this case it seems 
plausible to assume that conditions inhibiting further vegetative 
development of the fungus on diseased muskmelon vines, as 
well as the “adverse” environment of mycelium, introduced 
under a sliver of a pumpkin vine or similar host, tend to cause 
the production of the “perfect” spore-form. The dry condition of 
the substratum seems the important factor in the formation of 
the “ perfect ” spore-form. Lakon concludes that transpiration 
is the greatest single factor in causing the development of the 
fructification of Coprinus plicatilis, other factors being of im- 
portance only in so far as they accelerate transpiration. But 
in an Anhang to his paper he states that his fungus would not 
fruit on Vicia Faba—decoction agar though it did when stems 
of Vicia Faba were placed in agar-agar.*° 
Some of the above observations on immune cucurbits and the 
- pumpkin inoculations of 1907 (Plate XII) seem to indicate that 
certain conditions of environment may produce ascospores and 
be adverse to or check the formation of pycnidiospores. 
INOCULATION OF MUSKMELON AND WATERMELON. 
Mycelial inoculations.—About fifty inoculations were made 
in the field on each of both watermelon and muskmelon vines, 
which were large and vigorous. The mycelium, taken from a 
fresh potato-agar culture, was introduced under a vine-sliver 
which had been made by means of a tangential cut with a 
sterile scalpel. Half of the infections were covered with graft- 
% G. B. Lakon, Die Bedingungen der Fruchtkérperbildung bei Coprinus. 
Ann. Myc. 5: 155-176 (1907), Berlin. 
