126 REPORTS ON INVESTIGATIONS AND PROJECTS. 



DESERT BOTANICAL LABORATORY. TUCSON, ARIZONA.* 



Dr. W. A. Cannon, the resident investigator, carried out an inquiry 

 in the comparative anatomy of plants growing in dry and in irri- 

 gated soil, and among other results found that the irrigated indi- 

 viduals do not carry the development of the conducting system as far 

 as those growing under natural conditions. The greater capacity of 

 the conducting organs of the latter enables them to make use of the 

 rainfall during the brief period in which it is received. Observations 

 have been begun on the transpiration of salt-loving plants. 



Prof. F. E. Lloyd, of Columbia University, under a grant from 

 the Carnegie Institution of Washington, was in residence at the 

 laboratory from June i r to July 24, 1905. He continued his studies 

 on the stomatal action of Fouqideria splendens, which were begun 

 in 1904. He perfected a means of preserving the stomata in the 

 condition assumed by them in nature, and extended and verified by 

 numerous experiments the conclusions reached in his earlier studies. 

 His investigations lead to a new interpretation of the essential nature 

 of the guard cells of the stomata. Further details concerning his 

 work may be found in his report. 



Dr. V. M. Spalding, under a grant from the Carnegie Institution, 

 occupied a table at the laboratory from October, 1904, until April, 

 1905, continuing his investigations on the biological relations of 

 desert shrubs. He showed that there is a very intimate relation 

 between the rate of transpiration and the character of the water 

 supply and established the necessity of determining the water 

 relations when the effect of any stimulus (as sunlight) on the rate of 

 transpiration is in question. He also investigated the absorption of 

 water by the leaves of various desert plants. In addition to the 

 investigations mentioned above, he began a botanical survey of the 

 immediate locality, including the laboratory tract, and laid the 

 foundations for a thorough study of this subject. 



Mrs. Eflfie Southworth Spalding continued her observations on 

 the adjustment of the giant cactus to various external factors. In 

 the preceding year an investigation was made on the changes which 

 this cactus undergoes with a variation in the amount of water stored 

 up in its tissues. During the present year the influence of temper- 

 ature variations as well were observed and measured. A means of 

 measuring changes in height, with special reference to growth, was 



* Grant No. 220, (For first report, see Year Book No. 2, p. xxvi ; for second 

 report, see Year Rook No. 3, p. 98-100.) 



