Wilson : North American Peronosporales 
77 
genus. No oospores were found. The pedicel adhering to the 
conidia suggests a relationship with P. Colocasiae , although it is 
a distinct species, and apparently quite dissimilar to the average 
run of the oriental species of the genus. 
The latest addition to the list of pests referred to this species 
was first reported by Hori (1907) as attacking ginseng in Japan 
and in Ohio. Since that time it has been found to be a wide- 
spread pest in ginseng beds in the United States. This fungus 
is certainly incorrectly identified. It is described as having simple 
conidiophores measuring 95 X 7/* and emerging from the 
stomata. The conidio are elliptic to ovate, 30-50 X 50-60 /a, 
prominently papillate, and having a very short basal pedicel. The 
oospores are thick walled, light brown in color, and measuring 
26-28 [X. 
Species Inquirendae 
Three additional members of the genus have found their way 
into literature, yet are of doubtful standing on account of their 
improper introduction. Mention is made by Gandara (1909) of 
a P. Agaves Villada on the mayguey in Mexico, but no description 
or figure is given of the fungus. P. Jathropiae Petersen has been 
distributed by the “ Centralstelle fur Pilzkulturen ” but is as yet 
undescribed. An unnamed species of Phytophthora is men- 
tioned by Moller (1901) as occuring on the “figs imported from 
Europe to Brazil ” and at least locally causing considerable 
damage in gardens. The liminiform conidia are prominently 
papillate and measure 38-45 X 100-200 fi. The conidiophores are 
100-200 fi high. The relationship of the fungus is quite obscure 
as the only species of the genus with which he appears to have 
been acquainted is P. infestans. The fungus may be an European 
export, in which case it is probably closely related to the other 
fruit-rotting forms. 
Cross Inoculations 
One of the most interesting results of the work on species of 
Phytophthora in the last four or five years is the peculiar and 
altogether unexpected outcome of the numerous cross-inoculation 
experiments. A comparison of the results published by the vari- 
