794 Lloyd, The Desert Botan. Laboratory of the Carnegie Instit. of Washington. 



the various methods of promoting research by the Board of the 

 Carnegie Institution, and at its close, a plan was proposed by the 

 President, Professor Woodward, by which the resources of the 

 Institution are henceforth to be used chiefly in forwarding the 

 investigations in progress at the various special stations and Labo- 

 ratories which have been founded under its auspices, in contra- 

 distinction to the making of a large mnnber of small special grants. 

 Thus the Desert Botanical Laboratory becomes now the centre of 

 a Department of Botanical Research, and the Directorship has been 

 given to Dr. D. T. MacDougal, recently Assistant Director of 

 the New York Botanical Garden, and a member of the original 

 advisory eommittee. 



The city of Tucson, near which the Laboratory Stands, with a 

 population. of 15000 is situated in the valley of the Rio Santa 

 Cruz, its position being central with respect to the deserts of Cali- 

 fornia, Mexico, Texas, New Mexico and Northern Arizona, an area 

 embracing 12° of latitude and 16° of longitude roughly speaking. 

 With an elevation of 2,390 feet above sea level, it has a dry and 

 bracing climate, and thought hot in the summer, still an account 

 of the low relative huniidity, not uncomfortable. The soil is a fine 

 clay or u adobe" underlaid in most of the area by a hard pan of 

 white material derived by the leaching out of the soil, and known 

 locally a "caliche". Without doubt, wherever this caliche occurs 

 it is a prominent factor in the determination of the character of 

 the Vegetation. Two niiles to the westward are to be seen the 

 out posts of the Tucson Mountains, rugged hüls of volcanic origin. 

 ( mi the more gradual northerly face of one of these stands the 

 laboratory, a building appropriately constructed of volcanic boulders. 

 The style in simple and well adapted to the climate. The thick 

 stone walls heat slowly, particularly as they are for the most part 

 protected from the direct rays of the sum by a widely overhanging 

 roof. This latter is so constructed as to form a large ventilatel 

 air chamber, thus affording a protection against the intense inso- 

 lation as well as affording comfort to the occupants by modifying 

 the intense Light. 



The original building was in the form of the letter L with the 

 longer extension facing the north. At the present time an addition 

 is approaching completion which doubles the capacity of the buil- 

 ding. The main portion, facing the north is 126 feet long, two 

 lateral wings extending southward from either end to a length of 

 • 11) feet, The new wing will be in part a glass house 20 feet long 

 for experimental pnrposes. The breadth of the main portion of 

 the building is 23 feet, of the wings 19 fced. The inferior is sui- 

 tably broken up into rooms, including a main general laboratory, 

 offices, stock-rooni, Photographie dark room, constant temperature 



