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207 
Phytopthora infestans, De Bary. 
It is now generally admitted that this fungus does not 
produce oospores or resting-spores in a state of nature, 
but that for some unknown reason, probably owing to 
having resting mycelium present in the tubers of its host- 
plant, this stage has been suppressed as superfluous. Quite 
recently Clinton, an American mycologist, has succeeded 
in producing oogonia and antheridia of this fungus in pure 
cultures, oospores were present in the oospheres, but no 
evidence of fertilisation was observed, and no germination 
of the oospores resulted. Science, N.S., 33, p. 744 (1911). 
Pethybridge and Murray have corroborated Clinton’s 
observations, and added some important points ; from 
their cultures it appears that the oogonium penetrates 
and grows through the antheridium as in Phytophthora ery- 
throseptica, described above. No germination of oospores 
has been observed, and if fertilisation occurs, it must 
precede the formation of the oosphere. a point hitherto 
unknown in the Peronosporaceae. 
Scient. Proc. Roy. Diiblin Soc., March, 1913. 
Peronospora potentiilae, De Bary. 
Tufts more or less dense, sometimes softish, at hrst 
whitish then greyish-brown or dingy violet ; conidiophores 
slender, densely tufted, 300^—600 x 7—8 p, 5-—6 times 
branched above, the lower and median branches spreading, 
forming acute angles, ultimate and penultimate branches 
spreading, tips often recurved ; conidia elliptical, 20—25 
X 15^—18 p, tinged violet ; oospore with a smooth, yellow¬ 
ish wall. 
Syn. Peronospora ruhi, Rab. 
Peronospora jragariae, Roze and Cornu. 
On leaves of Potentilla anserina, P. argentea, P. jragaria- 
stri, Alchemilla vulgaris, Sanguisorha eupatoria, Fragaria 
vesca, Rubus caesius, Ruhiis iruticosus, Poterhim san- 
guisorba. 
Britain, Europe generally, N. America. 
This species is included in the body of the book by mis¬ 
take, as not having occurred in Britain. 
Uromyces lilii, Fuckel. 
Pycnidia. Yellowish-brown, mixed with the aecidia. 
Aecidia. Occurring on both surfaces of the leaf, most 
frequently on the under surface, also on the petioles and 
stem, on yellowish or brownish-yellow spots, in roundish 
