Page:Popular Science Monthly Volume 66.djvu/333

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WO years ago the Carnegie Institution determined to establish a laboratory to be devoted to the special study of desert vegetation. The plan originated with Mr. Frederick V. Coville, who, under the auspices of the Smithsonian Institution, had for some dozen years previously been a close student of the plants of the southwestern American desert. His interest was fixed by his experiences as a member of the memorable Death Valley Expedition of 1891. After Mr. Coville's plan had been adopted by the Carnegie Institution, an advisory board, consisting of Mr. Coville and Dr. D. T. MacDougal, was appointed. The first work of this board was the choice of a proper site—a task which will be conceded to be neither easy nor unimportant when the great extent and variety of the North American Desert is appreciated. Both of these gentlemen were, however, possessed of wide personal knowledge and experience of this region and brought to the solution of the problem ripe judgment. After a further personal examination of all of the most promising areas, including the deserts of Texas, northern Chihuahua and Sonora in Mexico, New Mexico, Arizona and of California, the choice rested upon Tucson, in southern Arizona. The results of this investigation are embodied in an extensive report which is full of valuable data and most instructive and beautiful illustrations. The wisdom of the choice of the advisory board may very naturally be questioned, and I confess to have entertained some doubt in this regard. After a personal examination, however, of nearly all the above mentioned regions, and after spending the major portion of the past summer at the Desert Botanical Laboratory, I am now of the opinion that the action was well-advised and is fully justified. I am therefore taking occasion at this time to give an account of the laboratory and its surroundings from my own point of view.

The city of Tucson, with a population of 10,000, is situated in the valley of the Santa Cruz. Its position is central with respect to the deserts of California, Mexico, Texas, New Mexico and northern Arizona. With an elevation of 2,390 feet above sea level, it has a hot, though dry and bracing, climate. The soil is a fine clay or adobe, underlaid by a white hard pan, locally known as caliche. Two miles