54 re;ports on investigations and projects. 



Movements of Vegetation Due to Submersion and Desiccation of Areas in 



Arid Regions, by D. T. MacDougal. 



The observations and experiments upon the occupation of the strands, 

 uncovered by an average yearly recession of about 50 inches, have now been 

 carried through six years. Strips as wide as 1,400 feet have been laid bare 

 on the shores with gentlest gradient, while on precipitous slopes the strand 

 is less than a dozen feet. The amount of soluble material in the lake water 

 has increased from 0.33 per cent to nearly 0.9 per cent, so that a series of 

 beaches is present five, four, three, two, and one year old, each left sat- 

 urated with the lake solution of the year of its emergence and showing stages 

 of occupation correspondent with this condition of the substratum and with 

 its age. The hilltops emersed as islands offer evidence of the most vivid 

 interest as to the means by which plants are carried across barriers to distant 

 unoccupied areas. One new line of observation was made by motor from 

 Mecca southward along the western side of the lake to the cultivated lands 

 along the New River in June, while the islands were visited by a launch late 

 in the year. 



VARIOUS INVESTIGATIONS. 



Physical and Botanical Features of Sudanese and Libyan Deserts, by 



D. T. MacDougal and G. Sykes. 



In accordance with plans perfected early in 191 1, Mr. G. Sykes proceeded 

 to London, and in addition to carrying on some bibliographical work in the 

 British Museum, preliminary arrangements were made for an examination 

 of the region between the Red Sea and the forks of the Nile, and of the 

 Ivibyan Desert to the westward of the lower Nile. The members of the 

 expedition proceeded to Cairo via Brindisi and Port Said early in January. 

 Port Sudan, on the Red Sea, was reached by steamer from Suez in mid- 

 January, and after a brief inspection of the short coastal slopes of the moun- 

 tains, which rise to an elevation of over 5,000 feet, a special car, accom- 

 modating three persons, and which would serve as a moving laboratory, was 

 chartered for the trip from the coast to the Nile at Atbara and southward 

 to Khartum. This plan gave opportunities for observations at Sal Lom, 

 Kamobsana, Sinkat, Talgwareb, and Atbara, in the eastern desert, and it was 

 possible to gain a comprehension of the principal features of this arid region 

 within a comparatively brief time. 



The slopes toward the Red Sea offer many of the surface features char- 

 acteristic of the arid regions of Arizona and Sonora. The streams sink into 

 the loose debris which fills the "khors," or washes, making an underflow, the 

 possibilities of which have hardly been tested by those who are occupied 

 with plans for agricultural development. The vegetation comprises a large 

 number of species, in which the euphorbias and aloes comprise the succu- 

 lents so strongly represented by the cacti in America. 



