Botanical Features of North American Deserts. 

INTRODUCTION, 
Botanical science in its technical and applied branches has reached 
a stage of development in which it has become plainly evident that 
adequate progress in research in physiology, in comprehensions of life- 
histories, and in formulating the general principles governing the origin, 
environic relations and distributional movements of plants may be 
expected only by experimental methods in the field or in actual contact 
with the types of plants under consideration under normal environmental 
conditions. 
In no part of the subject is this so imperative as in the study of the 
xerophytic and highly specialized forms characteristic of the desert 
regions of the world, which comprise a total area equal to that of a large 
continent. The aridity, widely ranging temperatures of soil and air, 
physical and chemical properties of the soils, conditions of insolation and 
radio-activity, together with the special forces modifying distribution, 
furnish a set of conditions not easily duplicated by the regulation of the 
artificial climates of glass-houses and not adequately represented by pre- 
served material in herbaria and other collections. A European botanist 
of ability scarcely lays down his work at the endof a life of zeal and indus- 
try devoted to the study of the cacti under cultivation in a climate 
entirely foreign to them, when an examination of these peculiar forms in 
their native habitats reveals the necessity for a complete repetition of the 
entire investigation. 
When the Carnegie Institution of Washington was established, Mr. 
Frederick V. Coville determined to present to it a plan for a Desert 
Botanical Laboratory. This long-cherished project was an outcome of 
his work in the Death Valley Expedition, in 1891. <A plan was accord- 
ingly drawn up by him and presented to the Institution’s Advisory 
Committee in Botany. This committee considered and approved it 
because it promised results concerning the fundamental processes of pro- 
toplasm as important as any in the whole realm of botany. The Board 
of Trustees of the Institution also gave their approval to it, and appropri- 
ated $8,000 for the establishment of such a laboratory and its main- 
tenance for one year. Messrs. Coville and MacDougal were appointed 
by the Institution as an Advisory Board in relation to the matter. This 
Board decided to place the Laboratory under the immediate charge of a 
resident investigator, who should carry on researches under its guidance, 
and should be responsible to it in his relations to the Institution. It was 
I 
