OSMOTIC CONCENTRATION OF SAP. 2OJ 



Note that these values are actually slightly in excess of those 

 determined from the leaves of the trees collected on the same 

 dates. 



A tree of A. nitida about 16 cm. in diameter on the mainland 

 shore of Biscayne Bay at Miami gave: 



Feb. 24, A == 2.76, P = 33.1 



This constant is distinctly lower than any of those determined 

 at Port Henderson, and indicates that the latter values are in- 

 fluenced by the growth of the plants under the general environ- 

 mental conditions which have resulted in the development in 

 this region of the coastal desert flora (Harris and Lawrence, '17). 



B. Rhizophora mangle L. 



Rhizophora was not abundant on the Jamaican coast where 

 our collections were made. The shrubs occurred only in the 

 swamp. The constants determined were: 



Jan. 22, A == 2.47, P = 29.6 

 Jan. 25, A == 2.57, P = 30.9 

 Mar. 26, A == 2.43, P = 29.2 

 Mar. 30, A == 2.53, P ---- 30.4 

 April 2, A == 2.49, P = 29.9 



Average, A = 2.50, P = 30.0 



Small trees of R. mangle on the mainland shore of Biscayne Bay 

 yielded leaves which gave the following concentrations: 



Feb. 8, A == 2.20, P = 26.4 

 Feb. 17, A == 2.24, P ---- 26.9 

 Feb. 24, A = = 1.95, P ---- 23.4 



Average, A == 2.13, P = 25.57 



On the prairie below Florida City Rhizophora grows in a sub- 

 stratum where the amount of salt in the soil must be insignifi- 

 cant. Here the constants were found to be: 



Feb. 18, A == 1.85, P == 22.2 

 Feb. 29, A = : 1.84, P = 22.1 

 Feb. 29, A = 1.91, P = 22.6 



Average, A = 1.87, P = 22.30 



