1909] CURRENT LITERATURE 307 
meet factors of whose value we are ignorant. That ignorance needs emphasis. 
To say—‘‘anisophylly is to be looked upon as a special case of anisomorphy, by 
which we understand, with WresNER who proposed this term, that fundamental 
property of living substance in consequence of which the different organs (in 
our case the foliage leaves) have the power, each according to its position toward 
the horizontal or toward the parent axis, to assume different typical forms’”’— 
is merely to cloak ignorance with pedantry.—C. R. B. 
Desert vegetation 
A very fitting celebration of the fifth anniversary of the establishment of the 
Desert Laboratory was the publication of a treatise on North American deserts 
the number of valuable contributions emanating from Tucson. e contribution 
here considered includes some of the matter that made up the body of the first” 
Teport on our desert region by CoviLLE and MacDovucat in 1903 (Publication 6), 
but the great amount of new material, based on subsequent explorations and on 
the investigations at Tucson, made imperative the publication of a general treatise 
of this sort. An account is given first of the earlier investigations of the institution 
and the development of the department of botanical research, especial attention 
being directed to problems of long continuance, such as the study of the revegeta- 
tion of the Salton Basin and experiments on acclimatization. Nearly half of the 
work is devoted to a general account of the various desert regions of North America, 
including the various Mexican deserts, the northern sage-brush deserts, the 
Mohave desert and Death Valley, the Sonoran and Colorado deserts. Then 
follows a sketch of the geological features of the region about Tucson, by Professor 
Og BLAKE, territorial geologist of Arizona; herein is contained an account 
of the soils, including the caliche, an interesting calcareous formation arising 
through deposition from waters percolating upward. An interesting sketch 
is given of the seasonal changes in the aspect of the vegetation about Tucson. 
The early winter rains stimulate the development of a number of winter perennials 
and annuals. In the spring and early summer the aspect is controlled by more 
X€rophytic spinose and succulent forms, notably the cacti. The humid mid- 
summer, like the winter, is characterized by a number of forms stimulated to 
development by the greater moisture. ‘The treatise closes with a consideration of 
‘emperatures of plants in the desert (it being suggested that the great difference 
between air and soil temperatures is likely to be of significance), the water relations 
of desert plants, soil relations of desert plants, conditions contributory to deserts, 
and some general remarks on the formation and extent of deserts and the influ- 
“nce of the desert on life. This treatise will be a sine qua non for all ecological 
Workers, since it brings together what is known concerning our deserts, taking 
*MacDoucat, D, T., Botanical features of North American deserts. Carnegie 
Institut : 
‘stitution of Washington, Publication 99. 19 
