l8 CARNEGIE INSTITUTION OF WASHINGTON. 



for future activities, as well as for accounts of the work of departmental 

 associates and collaborators. Only the briefest summaries, indicating some 

 of the salient features of these accounts, are attempted in the following 

 paragraphs. 



The geographical range of the work of this department, which centers 



in the Desert Laboratory at Tucson, Arizona, has been extended during 



the past year to include certain portions of the deserts 



Department of £ nort h ern Africa. Thus Dr. Cannon spent the late 



Botanical Research. . * 



autumn and early winter of 1911-1912 in the deserts of 

 Algeria, while Director MacDougal and his engineer, Mr. Sykes, spent a 

 good share of the winter of 1911-1912 in the Libyan deserts. These expe- 

 ditions enabled the department to acquire extensive information for com- 

 parative studies of desert areas, and Dr. Cannon's report on the results of 

 the earlier expedition has been already received for publication. 



Studies have been continued also at the Desert Laboratory, at the Carmel 

 Laboratory on the California coast, at Salton Sea, and at various substations 

 where observations are made on the phenomena presented by plants under 

 strikingly varying conditions. The desiccation of the Salton Sea now under 

 observation presents many instructive conditions which are being carefully 

 studied in their climatic, biological, and physical aspects. It will be practi- 

 cable, therefore, in the course of a few years, to furnish something like a 

 detailed history of this remarkable basin, which has now been carefully 

 studied at intervals since its discovery in 1854 by the late Professor N. P. 

 Blake. 



One of the most important investigations undertaken during the past year 

 is that of a comprehensive study of the large and highly diversified family of 

 cactus plants. Through the cooperation of Prof. N. L. Britton, Director of 

 the New York Botanical Garden, and Dr. J. N. Rose, of the staff of the 

 Smithsonian Institution, who have been appointed Research Associates, it 

 will be practicable, by aid of the facilities of the department, to produce a 

 monographic study of these typical desert plants. 



Several volunteer associates and collaborators of the department have par- 

 ticipated in departmental researches and contributed to the progress attained 

 therein. Upwards of twenty individuals have taken part in one or more 

 phases of this work. 



The advances made by this department during the past year have been 

 chiefly along the lines of studies in cytology, in the chemistry of pigmenta- 

 tion, in the factors of mutation, and in the problems of 

 Department of Ex- i luman heredity. These studies have been carried on by 



penmental Lvolution. , J , J 



aid of experiments with plants and animals and by aid of 

 rapidly accumulating statistical data concerning human traits and their trans- 

 mission through successive generations. The Director has been able to give 

 much of his time to studies in human heredity by reason of his connection 

 with the Eugenics Record Office, whose work has been liberally supported 



