124 REPORTS ON INVESTIGATIONS AND PROJECTS. 



Topographical and Geological Survey of the Laboratory Tract, by Prof. 

 C. F. Tolnian. — In the investigation of the movements and distribution of 

 desert vegetation by Professor Spalding it was found necessary to secure a 

 map of the tract on which experiments are being carried out, and this was 

 undertaken by Professor Tohnan, assisted by some of his students from the 

 University of Arizona. 



Studies in Transpiration, by Dr. B. B. Livingston. — During the year the 

 investigation of the relations of plants to soil, moisture conditions of the soil, 

 and air, described in the Year Book for 1905 (4, p. 128), have been repeated 

 as to certain details to obtain confirmatory evidence while reading proof of the 

 completed paper upon the subject which has appeared as Publication No. 50 

 of the Institution. 



Dr. Livingston's researches have the ultimate purpose of determining in 

 a comprehensive way the entire water-relations of desert vegetation. In 

 this work it is of the greatest importance to secure a continuous record of 

 the evaporation of water from some adopted standard of surface, and an 

 evaporimeter, the initial design of which was made in 1905, has been devel- 

 oped until now a complete and continuous tracing may be obtained which 

 will be of the greatest importance in researches of many kinds in progress at 

 the Desert Laboratory. 



In the further unification of results it becomes necessary to ascertain to 

 what extent the available records of transpiration obtained from separated 

 branches are comparable with those obtained from entire plants under fairly 

 normal conditions. The accomplishment of this result will do much to 

 standardize results and reduce much apparent incongruity as to existing 

 conclusions. 



The study of the rate of transpiration displayed by various species shows 

 that much diflference exists among separate forms as to the physiological 

 regulation of transpiration. The detection of these differences becomes 

 possible by the use of the curves obtained from the recording evaporimeter 

 noted above. It is proposed to extend these observations to include repre- 

 sentatives of the more prominent types of xerophytic and other vegetation. 



Annotated Bibliography of Literature Relating to Evaporation, by Mrs. 

 Grace J. Livingston. — ^The fragmentary condition of the literature on evap- 

 oration rendered a bibliography of the subject necessary before much advance 

 could be made in a comparative study of the subject, or a development of 

 new methods, and the results at hand now include nearly seven hundred 

 legitimate titles. 



Physiology of Stomata, by Prof. P. B. Lloyd. — The experiments of the 

 previous summer (1905) have been repeated, as have also the observations on 

 the normal behavior of stomata and the changes in the content of the guard 



