DEPARTMENT OE BOTANICAL RESEARCH. 51 



The total solids increased about 17.5 per cent during the year ending June 

 3, 1912, the increase for the preceding year being 19 per cent. The calcium 

 content of the water increased but 10.6 per cent, the difference between this 

 and the total increase being ascribable to the action of bacteria as revealed 

 by Dr. Brannon in the succeeding section of this report. Sodium has in- 

 creased 18.9 per cent, while potassium remains stationary and does not appear 

 in the increase of the total dissolved solids. Thus in 1908 this element was 1 

 part in 158 of the total solids, while it is but 1 part in 222 in 1912. The 

 aberrant rate of variation of calcium has been shown to be due to biological 

 agencies, but it is not certain whether purely physical reactions or organic 

 absorption play a part in the disposal of the potassium. However, it is 

 shown conclusively that the concentration of a body of water like the Salton 

 Lake is not simply a matter of evaporation, crystallization, and chemical 

 interaction. 



The Surface Geology and Soils of the Salton Sink, by B. B. Free. 



A general examination of the surface of the slopes of the basin has been 

 made by Mr. E. E. Free, and analyses have been made of samples of soils 

 which must be taken into account in the determination of the character of 

 the run-off into the lake, and also as to the chemical and physical features 

 offered by emersed strands around the receding lake. 



Alterations in Woody Tissues and Bacterial Action in Salton Water, by 



M. A. Brannon. 



The recession of the waters of the Salton Lake, which began in 1907, 

 uncovered areas on which a vegetation chiefly composed of desert types was 

 growing before the submergence. The emersed plant-remains comprised 

 chiefly Prosopis juliflora D. C, Prosopis pubescens Benth., Covillea triden- 

 tata Vail, and a few specimens of Populus deltoides Marsh. 



Stems of Prosopis and Covillea representing the emergences of every 

 season up to and including that of 191 1, as well as living material, were sent 

 to Dr. Brannon, who was at work in the botanical laboratories of the Uni- 

 versity of Chicago in September 191 1. Carboys of water were also provided 

 for the experimental study of the action of the water. Specimens of a 

 single kind of wood were placed in separate carboys of pure Salton Sea 

 water and duplicate cultures were made in Lake Michigan water. These cul- 

 tures were maintained at room temperature and carefully observed during a 

 period of six months. Within two weeks after the cultures were made there 

 was evidence of changes in the Salton Sea water and in the specimens im- 

 mersed in the culture carboys. Much sulphureted hydrogen escaped from 

 the carboys when they were opened, and the cell-walls in the region of the 

 cambium were broken down. The processes leading to these two results 

 advanced steadily until a static condition in the sulphates of the cultures had 

 been established. During the transition periods large quantities of hydrogen 



