264 BOTANICAL GAZETTE [SEPTEMBER 
the Calluna maintains its dominance over both the grasses and the lichens. — 
Geo. D. FULLER. 
The variable desert.—Writing in semipopular language, Harris’? has 
described the wide variation of climatic and other factors infloenchig plant 
life in the desert region of Tucson, Arizona, in such a way as to give a more 
graphic and living a - this most interesting region than will be found in 
other more vol lreports. The wide variation of precipita- 
tion from year to year and from month to month is made clear by a diagram, 
while the large proportion of waste of the scanty water supply is emphasized. 
The wide range of temperature during both the year and the day, the almost 
urge: ‘qeeeed o pat forms, extending from thin to thick-leaved herbs, from 
hrubs, and from succulent to woody plants with varied 
aspect at different seasons of the year, are all clearly depicted. In a word, the 
reader is made to appreciate some of the complexity of environment and 
diversity of organisms which have rendered this region so fascinating to the 
intelligent layman and to the investigating scientist.—Gro. D. FULLER. 
: Ecology of lichens.—In connection with a systematic study of the lichen 
flora of South Lancashire, WHELDON and Travis* discuss some of the factors 
detrimental to the growth of these plants. Particular attention is directed 
to their sensitiveness to pollution of the at ical 
fumes attendant upon the development of a | mnautactacag industry. The 
observations are of a general rather than of a particular character and are not — 
—— by any experimental data. They also note that a calcareous 
substratum ratum seems to counteract the effect of smoke upon the lichens. = 
oe 
4 
baciciangh - scarier r 
| 7 to the carboniferous limestone.—Gro. D. FULLER. 
=r? ws? 
rt ‘i... Ate L E ea tae sly OR ee st £. 
: per commoner yas Ciedoagengeaaey Burns concludes that “‘toler- 
ance: Uaed te experas.& light relationship should no longer be used in reference 
te pment seedlings. He found the filtered light in the forest. 
ee pea a es zy +s , nm di ide com i with the w k- og 
. ened white light. in vay mau gh cp may 
ge oe ae oe ae SORES 1 eS D.1 ig ‘ 
a J. Anruve, Ths tie st Scientific ¢ Monthly 341-49. 16 ee 
33 WHELD A., and Travis, W. G., The lichens of South Lancashire. Jour 
. Lina. Soe. airih 1QT5. 
_eBems, GP, Std intolerance of New England forest is om 
continuous light in forests. Vt Sta. Bull. 193. pp. 23- 191 
