498 



J. ARTHUR HARRIS 



The table brings out clearly two facts: 



1. That in all four families and in both Jamaica and Florida, the 

 osmotic concentration of epiphytic forms is extremely low. 



2. That for the three groups represented in both regions the os 

 motic concentration of the epiphytes (chiefly from the hammocks) of 

 subtropical Florida is higher than that demonstrated in the Jamaican 

 rain forest. The average difference is 1.57 atmospheres higher for 

 the Bromeliaceae, 4 1.74 atmospheres higher for the Orchidaceae, and 

 o. 24 atmospheres higher for the single species of Peperomia. 



The comparison may be made somewhat more analytically on 

 the basis of the means for the genera. 



The constants in table 2 are averages of the species means of each 

 of the genera. 



TABLE 2 



Genera of Jamaican and Floridian Epiphytes Arranged in the Order of the Average 

 Osmotic Concentration of Their Species 



4 That the higher value for Floridian Bromeliaceae is not primarily due to the 

 inclusion of Dendropogon usneoides (= Tillandsia usneoides) is shown by the fact 

 that if this species be omitted from the Florida series, the remaining 9 species average 

 A = 0.433, P = 5.19, which are respectively o.ioo and 1.19 greater than the Jamaican 

 average. 



