DEPARTMENT OF GENETICS. 153 



Miami (Florida), and on the eastern coast of the Gulf of Mexico. 

 In 1917 work by boat was carried out from Miami to Fernandina, 

 Florida. In 1919, Dr. Harris, accompanied by Mr. John V. Lawrence 

 and Mr. M. C. E. Hanke, covered the territory between Norfolk, Vir- 

 ginia, and Miami, Florida. In 1921, one month was devoted to work, 

 on a small yacht placed at Dr. Harris's disposal by a friend, on the 

 vegetation between Charleston, South Carolina, and Miami, Florida. 

 Messrs. A. T. Valentine and C. W. Crane assisted in these field opera- 

 tions, in which particular attention has been given to the changes 

 in typical halophytes as they extend up the fresh-water courses, and 

 to typical fresh-water species as they reach the hmits of their distri- 

 bution seaward. Reports on the results are waiting the completion 

 of analyses. 



These investigations have been facilitated by the cooperation of the 

 Department of Botanical Research. 



Studies on the physico-chemical properties of the tissue fluids of cereals 

 under irrigation and under dry-farm conditions. — Work on the changes 

 in the properties of the tissue fluids of the small grains during the 

 march of the season, carried out by Dr. Harris incidental to studies on 

 the native vegetation of the Bonneville Basin in 1920 (Year Book, 

 Carnegie Inst. Wash., 1920, p. 143), indicated the desirabihty of more 

 detailed studies. These were made possible by cooperative operations 

 with the United States Department of Agriculture and the Utah 

 Agricultural Experiment Station in 1921. Mr. W. F. Hoffman and 

 Mr. A. T. Valentine, field assistants, went to Utah early in June to 

 take up these studies, and Dr. Harris went to the field July 1. The 

 problem is essentially one of the capacity of the organism for adjust- 

 ment to environmental changes. Through the kindness of Professor 

 George Stewart and Mr. A. D. Allen, of the Utah Agricultural Experi- 

 ment Station, it was possible to institute comparisons between irri- 

 gated and dry-farm cereals. The problems under consideration are: 



1. Comparison of capacity for change in osmotic concentrations in 

 different cereal species in relation to the problem of survival and pro- 

 ductiveness under desert conditions. 



2. Comparison between different varieties within the same species to 

 determine whether growth and yield under desert conditions are related 

 to sap properties. 



Statistical Theory of Plot Tests. 



These investigations have been continued along hues indicated in 

 previous Year Books by Dr. Harris. An exhaustive study of the 

 permanence of differences between the plots of an experimental field 

 has been published by Harris and Scofield (Jour. Agr. Res., 20 : 335- 

 356, 1920), who have treated the data of 9 years' continuous cropping 

 at the Huntley, Montana, field station of the Office of Western Irriga- 

 tion Agriculture. 



