264 Researches into the Nature of the Potato-Fungus. 
in this direction, as well as the examination and comparison of 
the abundant material made known by the collectors of fungi, 
have always yielded a purely negative result. Phytophthora has 
not been observed on any indigenous species of Scrophulariaceoiy 
while Peronospora grisea, Unger. [P. sordida. Berk.), plentiful on 
species of this family, is entirely different from the potato-fungus. 
Here I may mention that this year I found the potato-fungus 
on an exotic species of ScrophulariacecB, viz. Schizanthus Gra- 
liami, on which, so far as I know, it had not been observed before. 
It appeared on this ornamental plant in a garden outside Stras- 
bourg, belonging to Dr. Stahl, in the end of July, when the 
potato-fields had been extensively attacked by it. The pheno- 
mena of destruction were the same as in the potato-plant in 
stalks, leaves, and buds ; the development of the fungus was 
of extraordinary luxuriance, but here, also, no oogonia were 
found. This example, at any rate, reveals to us a new host for 
the Phytophthora, and demonstrates the possibility of other species 
being found in which it may grow not only luxuriantly but also 
form oospores. The fact that Schizanthus Grahami is a Chilian 
plant, and, therefore, indigenous to the same region as Solanum 
tuberosum and its allies, may not, perhaps, be of any great 
importance in this connection, still it should be noticed. 
It is, perhaps, not very unlikely that the oospores of Phytoph- 
thora may, in a climate different from that of Central Europe, be 
found in hosts which do riot produce them with us. On that 
supposition the first place to turn to would be the native land of 
the potato-plant. But no further observations need be" made 
here on this subject, since it unfortunately belongs only to the 
region of speculation. 
Hibernation of the Potato-fungus. 
10. To the questions raised at the beginning of section 3 
(page 248), concerning the hibernation of the potato-fungus, and 
the manner in which it returns to the fields in summer, the re- 
searches described in the foregoing pages supply no answer, or, 
at least, not one in any way satisfactory. Even if the often- 
mentioned warty bodies were hibernating oospores of Phyto- 
phthora, like the similar oospores ol Peronospora Arenarice y/hich. 
resemble them, we should not gain much information bearing 
upon these questions, since their occurrence is, at the best, ex- 
traordinarily rare, while the potato-fungus appears plentifully 
every year. 
In all stages of the development and of the vital phenomena 
of tlie potato-fungus, as far as they are known, the parasite acts, 
apart from the obvious specific peculiarities, precisely as many 
