154 THE JOURNAL OF INDIAN BOTANY.
of which trees of nearly 300 ft. with a bole 150 ft. before the first branch
are common. Their slender trunks 30 ft. round, are covered with a white
mottled bark, so that the;/ " suggest the columns of some mighty cathedral."
Except in the region of these Karri the forest is open and park like, with no
thick or tall undergrowth— a Savannah woodland.
P. P. F.
Fungi.
Sundaraman, S., Usfcilago Crameri Koem on Setaria ifcalica Beauv. Bull. No. 97 of the Agr. Res. Inst. Pusa. *As. 4.
It has long been known that smuts of various kinds cause great loss in cereal crops and this is an account of the investigation into that of Setaria italica which is grown very largely in South India and more especially in the North Central districts of Cuddapah, Kurnool, Bellary, Anantapur and Guntur.
Mr. Sundaraman finds that the smut spores germinate freely in distilled water even up to 95 per cent, in 12 hours, but failed to germinate when placed in solutions of copper sulphate of 0. 5% for 15 to 30 minutes. The fungus enters the plant in the young seedling stage but does not infect the flowers and the grain is the only part in which it shows itself. Though some- times the upper spikelets may not show smut while those lower down do, in no case is the reverse found. This of course is because the fungus has entered the plant at the base and crept upwards. It will be seen that in no important detail is Ustilago Crameri different from species common in Europe. But the results are useful as confirmation of the life history of smuts and this kind of work is very necessary.
P. F. F.
Physiology.
Coville, Fredrick V. The Influence of Cold in stimulating the Growth of Plants. Jour. Ag. Res. 20 : 151-160. 1920.
For trees and shurbs of cold climates to become dormant low temperatures are unnecessary. But for the resumption of growth after dormancy chilling is required. The stimulating effect of cold is limited to the part of the plant exposed to cold. This effect is produced by the digestion of starch to sugar, due to the weakening of the cell-membrances which separate the enzyme from the stored starch. The accumulation of sugar hastens growth by virtue of the higher osmotic pressure imparted to the cell.
The author discovered, first in his work with blueberries and confirmed by observations on many other plants of the temperate regions, that shoots kept during the winter in a warm greenhouse fail to develop their dormant buds in the spring. A single freezing does not suffice to make the buds develop, but a period of two or three months of exposure to cold is required. This characteristic is a safety device which prevents the premature leafing and flowering of plants during warm periods in early winter and their subsequent death. The necessity of chilling explains why such fruits as apples and pears do not grow successfully in tropical regions. What the gardener speaks of as " resting " is often merely the period of chilling.
