Wilson: North American Peronosporales 
69 
smooth wall, and measuring 18.5-25^ in diameter. “Those seen 
by the writer,” says Clinton, “ did not differ materially from the 
oospores of P. Phaseoli, so that we may expect those of P. in- 
festans, when found, to be of similar character.” 
The fungus was not obtained in pure culture. Inoculations 
were made direct from the diseased leaves to the cut surface of 
potatoes and onto young tomato plants in the greenhouse. All 
failed, as did the attempts to produce the fungus on Thalictrum 
by inoculating it with a pure culture of P. infestans, which at the 
same time was able to infect potatoes. Concerning the identity 
of the present species and the results of his inoculations Clinton 
says, “ since P. Thalictri resembles P. infestans so closely, the 
writer has thought that possibly they might not be distinct species. 
Worthington G. Smith (Diseases of Field and Garden Crops, 
pp. 275-6) gives a list of different hosts of P. infestans which 
include even two Scrophulariaceae. . . . While these experi- 
ments were probably not extended enough to speak positively, 
still they at least indicate that these fungi are distinct strains, 
if not distinct species” (p. 895). Personally the present writer 
regards these experiments as far more conclusive evidence of 
the distinctness of the two species in question than would the 
success of any of these inoculations have been of the identity of 
these fungi. The question which is raised concerning the hosts 
of P. infestans has been noted under that species. 
The statement made by Clinton concerning the identity of P. 
Thalictri is misquoted by Dastur (p. 225) who speaks of “ P. 
Thalictri, which Clinton suspects to be identical with P. Phaseoli.’' 
8. Piiytophthora Fagi (Hartig) Hartig 
This fungus attacks the beech seedlings in Europe, often prov- 
ing quite destructive. It first attacks the cotyledons, then spreads 
to other parts of the plant. A large number of other tree and 
herb seedlings are known to be subject to the attacks of a 
Piiytophthora in Europe and it is not improbable that there is but 
a single species of the genus concerned in seedling diseases. 
This, however, has not been investigated in recent years. We are 
indebted to Himmelbaur for a careful comparative study of this 
