MILDEWS, RUSTS AND SMUTS 
15 
continuance from year to year. The zoospores, liberated 
from the conidia, are dispersed by rain, birds, animals, 
insects, etc., and infect neighbouring plants, thus promoting 
the rapid spread of the disease. The zoospores, however, 
are short-lived, and only facilitate the spread of the disease 
during the period that the host-plant is actively growing. 
The continuance of the parasite from year to year depends 
on the presence of mycelium in the tubers. When a tuber 
containing mycelium is planted, the mycelium grows 
in the tissues of the sprouts, and passes upwards through 
the stem into the leaves, where in course of time it produces 
the conidial form of reproduction on the under surface of 
the leaves. By means of hibernating mycelium in the 
tubers, the disease has been carried from place to place, 
and is now unfortunately present in every quarter of the 
world where the potato is cultivated. 
Abundant on the potato plant [Solanum tuberosum), 
also on the foliage of many other species of Solanum, both 
wild and cultivated, also on the tomato (Lycopersicum 
esculentum). 
De Bary, Journ. Roy. Agric. Soc. Engl., p. 12 (1876). 
Jensen, Mem. Soc. Agric., p. 131 (1877). 
Massee, Dis. Cult. PL, p. 123 
Ward, Diseases of Plants, p. 59. 
BASIDIOPHORA, Roze and Cornu 
Mycelium branched, running between the cells of the 
host-plant, and sending vesicular haustoria into the cells ; 
conidiophores stout, simple, tip swollen and bearing several 
broadly elliptical conidia, which produce zoospores on ger¬ 
mination ; oosphere furnished with a very thick, hard 
wall; oospore globose, coloured. 
Rea.dily distinguished by the simple, or unbranched 
conidiophores each bearing a cluster of large, almost sessile 
conidia at the swollen tip. 
Only one species known. 
Basidiophora entospora, Roze and Cornu. Forming 
ochraceous then brownish patches on the upper surface 
of the leaf, the corresponding areas whitish on the under 
surface ; conidiophores solitary or several, emerging through 
the stomata, stout, simple, tips swollen, 150—300 X 
12—15 p ; conidia broadly elliptical, tip papillate, springing 
in clusters from the swollen tips of the conidiophores, 
supported on very short, cylindrical stalks, colourless, 
