468 BOTANICAL GAZETTE [JUNE 
found similar situations in humid climates generally. The chief categories of 
natural formations are halophile, subalpine, alpine, and the sea-fowl cliffs, and 
all but the latter are further subdivided. The halophytic formations are much 
as elsewhere, and the subalpine formations are mainly those of ponds, swamps, 
moors, heaths, and cliffs. The cliffs are of much interest, since there is a luxuriant 
vegetation on sunny southern slopes, while there is a poorer vegetation, mainly 
of shade mosses, on north slopes. Of rather more interest than usual are the 
culture formations, the most important of which is the grass meadow. One of 
the most striking features of the islands is the roof vegetation, which has always 
been mentioned by travelers; the inhabitants thatch the roofs with grass turf, and 
very characteristic roof associations develop. ‘The custom of the people is to sow 
potatoes in cleared ground for two years, after which barley is grown, whereupon 
the field is left fallow; under the heading “‘ Metamorphic formations,’’ OSTENFELD 
traces the history of such areas into the grass meadow.—H. C. Cow Les. 
Some plant diseases.—LAnG'S has given a detailed account of the biology of 
Ustilago Tritict Jens., which, as BREFELD has shown, is peculiar and almost 
unique among the fungi on account of its habit of infecting the ovule and remain- 
ing dormant in the seed until the latter germinates. Lane finds that the spores of 
this fungus placed upon the stigmas of wheat flowers just opened germinate 
readily, but the germ tubes show no tendency to penetrate the stylar tissue. Only 
when the papillae of the stigma have begun to wither and collapse can the germ — 
tubes penetrate between the cells. The fungus apparently has no power of 
penetrating the sound turgid tissue, a fact which has an interesting bearing in 
view of the usually strict parasitism of the vegetative phase in this group. The 
germ tube, without branching, makes its way down the intercellular spaces of the 
style, or sometimes down the canal formed by the pollen tube, and penetrates the 
inner integument near the micropylar end, the outer integument having mostly 
disappeared by that time. When the hyphae reach the chalazal region, they 
become branched and nodular, apparently showing greater vigor of growth in the 
region of more abundant nourishment. About three weeks after infection the 
fungus has reached the embryo. At first it spreads through the scutellum, but 
later the mycelium pervades every part of the embryo except the radicle. This 
stage is attained simultaneously with the ripening of the grain. The mycelium 
remains dormant in the ripe seed, and, when the latter germinates, progressively 
infects the growing points of the plant, but causes no apparent injury until spores 
are formed in the ovaries. 
Gitssow"* reports the appearance in Newfoundland of a potato disease known 
as ‘‘cauliflower disease” or ‘‘potato-canker.” The disease is caused by a chytri- 
15 LANG, WILHELM, Die Bliiteninfection beim Weizenflugbrand. Centralbl. 
Bakt. II. 25:86-ror. pl. I (double). figs. 2. 1 
16 GUssow, H. T., A serious potato disease occurring in Newfoundland. Cent. 
Exp. Farm, Depart. Agric., Ottawa, Canada. Bull. 63. pp. 8. pls. 2. fig. I. 1909- 
