DEPARTMENT OF BOTANICAL RESEARCH.^ 



D. T. MacDoitgal, Director. 



The investigations carried on by this Department have been con- 

 fined to the main fields of research, to which attention has been 

 devoted for several years. 



The study of growth has led to a consideration of the phenomena 

 of imbibition and osmosis in protoplasm. The detailed action of 

 biocolloidal mixtures, living and dead cell-masses, and the changes 

 in volume of living plants of various types have been measured with 

 great accuracy by newly designed apparatuses, including the auxo- 

 graph, the dendrograph, and a new type of colloidal cell. 



The study of photosynthesis in the green cells of living plants and 

 carbohydrate metabolism in general has made such progress as is 

 possible in this complex and difficult subject. A small laboratory 

 especially designed for this work has been completed within the year 

 at Carmel, California. The equable temperatures of the region and 

 the constant-temperature chambers provided in this structure are 

 features of great value in such investigations. 



Researches on nutrition and metabolism have been devoted to the 

 phase of the subject in which sources of nitrogen, acidity, and balance 

 of the nutrient salts have been considered, while some attention has 

 been devoted to the sources of the vitamins and their action in the 

 organisms in which they originate. 



Studies in the development of root-systems have been carried 

 through to extensive, detailed, and accurate measurement of the 

 effect of soil-atmospheres upon the growth of roots. The rarer ele- 

 ments of the atmosphere, hehum and argon, have been used for the 

 first time as the neutral element in mixtures of atmospheric gases in 

 the place of nitrogen. 



The composition and behavior of the elements of the flora in a 

 desert area have been found to depend largely upon such soil condi- 

 tions as salt-content, course of temperature, and mechanical texture 

 of the soil. 



The examination of the vegetation of the more arid regions, as 

 part of the original purpose of the Desert Laboratory, has already 

 included field work in western America, Mexico, South Australia, and 

 northern Africa, and a party is now carrying out field work in South 

 Africa in cooperation with the Division of Botany of the Union of 

 South Africa. 



^Situated at Tucson, Arizona, and Carmel, California. 



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