476 BOTANICAL GAZETTE [JUNE 
Light measurements.—Following the well known methods of WIESNER, 
several careful investigations by RUBE have largely increased our knowledge 
of light conditions in alpine and desert regions and at sea. The most pro- 
longed of these studies was made at Bernina Hospice,’ a station in the Alps 
with an elevation of 2309 meters, where it has been clearly demonstrated that 
both the maximum light intensity and the light totals are greater than those 
for lower altitudes. The minimum light intensity at midday in the Alps is 
much higher than at Vienna, the ratio being 85:7; while a similar relation 
exists between the light totals. Other interesting items from the abundant 
data are the nearly equal values of direct and diffuse light during the growing 
period, the somewhat increased light intensity after precipitation, and the 
decidedly greater available light on southern as compared with northern 
slopes. Many of these data may prove valuable in interpreting alpine vege- 
tation. 
Observations made at sea" tend to show that the maximum light intensity 
differs meds from those of regions of low altitude on shore, but that the amount of 
iffuse light is somewhat greater. The characteristic of desert light conditions” 
appears to be the low light intensity both at full sunlight and with cloudy sky, 
an intensity which increases teams however, immediately after rainfall. 
This must have some influence in modifying the otherwise extremely xerophytic 
conditions, but the author seems to ‘ions other investigators of light phe- 
nomena in failing to recognize the influence of light upon transpiration. 
—Geo. D. FuLter. 
Work at Peradeniya.—The numerous publications issued from the Royal 
Botanic Gardens at Peradeniya indicate great activity, which naturally 
expresses itself chiefly in investigations connected with economic plants. 
Petcu, the mycologist, has found a very fruitful field for cultivation; recent 
Circulars dealing with “Brown root disease” (Hymenochaete noxia), which 
attacks several of the most important plants; “A root disease of Hevea 
(Sphaerostilbe repens), the Para rubber plant; “Root diseases of Acacia 
decurrens,” a plant extensively used as a wind-break for tea or for Bg 
manuring”’; “Root diseases of tea”; and “Cacao and Hevea ¢ canker.” In 
the Annals, the same author has presented a study of Lasiodiplodia,” showing 
ina striking way the confusion that has arisen among the subgenera of Dip ea 
*s RUBEL, E., Untersuchungen iiber das oS Klima des Berninahos- 
pizes. Viertl. Natf. Gesell. Ziirich 53:1-78. 1 
———, Beitrage zur Kenntnis des TT Klimas der Canaren und 
des Ozeans. Idem 54: 289-308. 1909. 
e , Beitraége zur Kenntnis des photochemischen Klimas von Algerien. 
Idem 55:91-102. 1910, 
8 PETCH, 7, On Lasiodiplodia. Ann. Roy. Bot. Gard. Peradeniya 4+ 2445-405- 
TQIO. 
