ECOLOGY AND PHYSIOLOGY OF THE RED MANGROVE. 



(Plates IV-IX.) 



By H. H. M. bowman. 



{Read April 13, 19 17.) 



General Statement. 



When the plan for the pursuit of these studies was considered 

 in the winter of 1914, the main idea was to make an effort to learn 

 a little about the physiology of these interesting viviparous plants. 

 Especially was it the aim to study the transpiration and absorption 

 relations of these trees growing in salt water. Accordingly the 

 splendid resources of the Carnegie Institution of Washington were 

 offered and in June of 1915 the work was begun at the Institution's 

 Marine Laboratory located in the Dry Tortugas. 



During the first summer considerable ecologic observation was 

 made during a month's stay at Key West, Florida, the institution 

 having furnished the investigator with a launch and two men. Many 

 observations were taken on the growth habits of the plants, the 

 character of the bottoms on which they grew, the depth relations, 

 tidal effects, the flowering and fruiting conditions, growth rates of 

 hypocotyls and of aerating roots, water densities, dimensions of 

 roots and aerial structures, heights of trees and general distribu- 

 tion about Key West and adjacent islands. 



In July, after going to Miami and thence down through the 

 Florida Keys on board the institution's yacht, Anton Dohrn, and 

 notes on the mangrove being taken at various keys on the trip, the 

 real laboratory work was commenced at the Tortugas. During the 

 six weeks' season of the laboratory, several trips were made up to 

 the Florida Keys for suitable plants and also for material on which 

 to work during the winter. At this time it was determined to en- 

 large the scope of the work and to study some of the anatomical 

 and histological features of Rhizophora mangle, and with this end 



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