EXPERIMENTAL EVOLUTION. 143 



factory methods for the collection and analysis of large series of samples have 

 been worked out. The analyses of the extensive series of samples collected 

 with the assistance of Messrs. Lawrence and Hanke in Dr. Harris's work 

 along the Atlantic Coast in 1919 (Year Book Carnegie Inst. Wash., 1919, 

 143) has now been completed and the results will be presented shortly. 



" (3) Sap properties of the vegetation of the Lake Bonneville Basin. — The most 

 extreme concentrations of the soil solution to which plants are exposed in their 

 struggle for existence are found in the basins of ancient lakes. In such 

 regions striking peculiarities of structure bear witness to the evolutionary 

 changes from the plant structures typical of mesophji,ic regions which have 

 been necessitated by the special environmental conditions. Of the available 

 regions, the basin of ancient Lake Bonneville, of which Great Salt Lake and 

 Sevier Lake are small remnants, affords the best opportunities for investigation, 

 both because of the wide range of environmental conditions and the relative 

 accessibility of the habitats. Furthermore, the classic geological studies 

 by Gilbert and the pioneer work on the indicator plants of alkahne regions 

 by Kearney, Briggs, and Shantz and their coworkers makes coordination with 

 other investigations highly desirable. The Biophysical Laboratory and the 

 Office of Drought and Alkali Resistant Plant Investigations of the Depart- 

 ment of Agriculture asked Dr. Harris to cooperate in the investigation of the 

 physico-chemical properties of the vegetation of this region, and he was 

 absent from Cold Spring Harbor from May 20 to September 7, 1920, while 

 engaged in this and associated projects. Mr. Andrus T. Valentine, of Cold 

 Spring Harbor, served efficiently as field assistant during the entire period. 

 Dr. R. A. Gortner, professor and chief of the Division of Agricultural Bio- 

 chemistry of the University of Minnesota, and Mr. Walter B. Hofmann, 

 instructor in agricultural biochemistry at the University of Minnesota, joined 

 in the field operations until August 1. Operations were then transferred to 

 the Cooperation Testing Station at Sacaton, Arizona, where facihties were 

 placed at Dr. Harris's disposal. 



"In the Great Salt Lake region about 750 determinations of osmotic con- 

 centration and specific electrical conductivity were made. Samples were also 

 preserved for chloride detennination. These was chiefly on native vegeta- 

 tion, but a considerable number was based on cereal varieties under investi- 

 gation on the dry-farming substation of the Utah Agricultural College and the 

 Office of Cereal Investigations of the Federal Department of Agriculture at 

 Nephi, Utah. Thanks are due to C. R. Ball, of the Department of Agriculture, 

 and to F. S. Harris, Director of the Utah Agricultural Experiment Station, 

 for permission to obtain material from this valuable series of cultures ; also to 

 ]\Ir. Bracken, the superintendent of the Nephi substation, for assistance in 

 obtaining materials. At Sacaton it was possible to secure valuable determi- 

 nations on the halophytic vegetation of the Gila River Valley, and also to 

 supplement our series of determinations on loranthaceous parasites by 

 determinations of electrical conductivity as well as osmotic concentration. 

 Dr. T. H. Kearney also placed his culture of upland and Pima Egyptian 

 cotton at our disposal, and it was possible to compare the sap properties of 

 these two types and of their Fi hybrids under as nearly as possible identical 

 conditions. Incidentally it may be noted that Pima Egyptian cotton is 

 probably the plant mutation of the greatest economic imiDortance, a 

 $20,000,000 crop having been grown in 1919. A crop of 200,000 acres, the 

 progeny of an original mutant individual, is now in the field. The results of 

 Dr. Harris's determinations in the field and in accessible cultures will be worked 

 up as rapidly as the computing and clerical force available will permit." 



