PHYSIOLOGY OF THE RED MANGROVE. 591 



and other islands by the current during the early spring season of 

 higher tides and, on being washed ashore, took root to eke out a 

 precarious and mostly fleeting existence. 



Almost the entire first half of the season of 1916 was devoted 

 to the biochemical research mentioned above. This work of testing 

 for various chemical substances in the hypocotyl or storage organ 

 of the seedling and the attempt at detecting enzymes in the organ 

 could most conveniently be pursued at this time. During the in- 

 terval which occurred from the time, in the early part of the season, 

 when the young plants needed for the transpiration work were gath- 

 ered and planted in the culture jars until they became established 

 in their laboratory condition, the chemical work was carried on. 

 Only after the plants had recovered from the shock of transplant- 

 ing and were reacting normally to their changed environment was 

 it deemed advisable to begin the transpiration work. 



At the close of the 1916 laboratory season in August, the investi- 

 gator accompanied the officers and crew of the yacht on her return 

 trip north through the Florida Keys to be placed in winter quarters 

 at Miami. On this journey of several days' duration, many distri- 

 bution notes were taken and maps made of the keys and the absence 

 of Rhizophora on certain keys carefully marked. 



After the yacht had been moored up to her dock in the Miami 

 River and shrouded in canvas for the winter, eight days were spent 

 making observations on Biscayne Bay, the Miami River and Arch 

 Creek on the admirable newly constructed launch possessed by the 

 institution, the Darwin. These observations were made with the 

 assistance of the yacht's chief engineer, Mr. John Alills, whose 

 skillful operation of the launch, often in shallow and difficult chan- 

 nels, and whose help with the instruments was much appreciated. 

 Tests by the hydrometer were made on the density of the water, 

 both top and bottom layers, from the open Atlantic, across Biscayne 

 Bay and up the Miami River and Arch Creek as far as any man- 

 groves extended. Material was gathered for later study of both 

 salt and fresh water trees and numerous transpiration records were 

 taken on the pneumatophore prop roots of the mangrove under 

 conditions and environments difficult for growth. 



In conclusion of this statement the writer wishes to acknowl- 

 edge the valuable aid given him by Professor J. W. Harshberger, 



