2 BOTANICAL FEATURES OF NORTH AMERICAN DESERTS. 
planned to begin a few inquiries of wide scope and important bearing to 
be carried on by the resident investigator until decisive results were 
obtained. 
THE LABORATORY LOCATION TRIP. 
Each member of the Advisory Board had visited, during the preced- 
ing twelve years, most of the more marked desert areas of the country. 
Nevertheless, it was deemed profitable to make, together, a systematic 
tour of these deserts, in order to gain a better comparative knowledge of 
the aspects of their vegetation and to select a locality offering the greatest 
advantages and facilities for the proposed work. Accordingly, between 
January 25 and February 28, 1903, they made a reconnaissance of the 
region along the Mexican boundary. As the outcome a site was selected 
on Tumamoc Mountain near Tucson, Arizona, and the erection of a lab- 
oratory building, according to plans approved by them, was begun. The 
organization of the laboratory was carried a step further by the appoint- 
ment of Dr. W. A. Cannon as resident investigator. 
In the absence of any publication dealing with the general features 
of American deserts, it seemed desirable to present the general results of 
observations made during the trip and include with them some of the 
information gained during previous work in deserts, illustrating the text 
with reproductions of landscapes showing characteristic vegetation. The 
paper embodying these features was brought out as publication No. 6 of 
the Institution in November, 1903. 
The establishment of the Desert Laboratory and the continuance of 
the examination of the arid regions has made available a much greater 
amount of general information concerning the extent and character of 
the vegetation of such areas. The newer contributions concern the sage- 
brush deserts of the Great Basin, in Nevada and in Utah, the tropical 
deserts in southern Mexico, the arid depressed basins of the delta of the 
Colorado River, the Sonoran Desert, the Cucopa Mountains, and the des- 
ert of San Felipe de Jesus, in Baja California. The results of the explora- 
tions of Hedin, Pumpelly, Willis, MacMahon, and Huntington in Asia, 
and of other workers in Australia and Africa, together with the fuller 
data noted above, permit some more satisfactory generalizations than 
had been hitherto possible. 
The edition of publication No. 6 (being the only attempt yet made to 
furnish a sketch of some of the characters of American deserts) having 
been exhausted, it has been thought advisable to include such portion of 
it within the present volume as might be necessary for completeness. 
This interpolation is made without special indication of the repetition, 
except in the plates. The character of the investigations taken up in 
connection with the main subjectis fairly indicated by the work described 
in the next section. 
