REPORT OF THE SECRETARY 105 



The water-culture method for growing plants without soil, by D. R. 



Hoagland and D, I. Arnon. 

 "Root-pressure" — au unappreciated force in sap movement, by Philip 



R. White. 

 The reproduction of virus proteins, by W. M. Stanley. 

 Modern medicine — the crossroads of the social and the physical sciences, 



by Charles Austin Doan. 

 History and stratigraphy in the Valley of Mexico, by George C. Vatllant. 

 The Folsom problem in American archeology, by Frank H. H. Roberts, Jr. 

 The Roman Orient and the Far East, by C. G. Seligman. 

 An ancient Chinese capital: Earthworks at Old Ch'ang-an, by Carl 



Whiting Bishop. 

 The natural limits to human flight, by H. E. Wimperis. 

 The historic American merchant marine, by Frank A. Taylor. 



Report for 1939. — The report of the Secretary, which included the 

 financial report of the executive committee of the Board of Regents, 

 and which will form part of the annual report of the Board of Regents 

 to Congress, was issued in January 1940. 



Report of the Secretary of the Smithsonian Institution and financial report 

 of the executive committee of the Board of Regents for the year ended June 

 30, 1939. ix-fl39 pp., 2 pis. (Publ. 3552.) 



The report volume, containing the general appendix, v/as in press 

 at the close of the year. 



SPECIAL PUBLIOATIONS 



Explorations and field-work of the Smithsonian Institution In 1939. 96 pp., 

 102 halftone figs, (Publ. 8586.) 



PUBLICATIONS OF THE UNITED STATES NATIONAL MUSEUM 



The editorial work of the National Museum has continued during 

 the year under the immediate direction of the editor, Paul H. Oehser. 

 There were issued 1 annual report, 27 separate Proceedings papers 

 from volmnes 85, 86, 87, 88, and 89, 1 Bulletin, and 1 Contributions 

 from the United States National Herbarium, as follows : 



MUSEUM BEPOBT 



Report on the progress and condition of the United States National Museum 

 for the year ended June 30, 1939. iii-f 128 pp. January 1940. 



PEOCEEDINGS : VOLUME 85 



Title page, table of contents, and index. Pp. i-x, 509-530. April 5, 1940. 



VOLUME 86 



No. 3065. Neotropical flies of the family Stratiomyidae in the United States 

 National Museum, by Maurice T. James. Pp. 595-607, fig. 71. August 3, 1939. 



