CONCENTRATION OF TISSUE FLUIDS OF EPIPHYTES 



497 



A = 0.32, P = 3.9; Feb. 24, A = 0.36, P = 4.4; Mar. 2, A = 0.37, 

 P = 4.5; Mar. 4, A = 0.38, P = 4.5; Mar. 13, A = 0.40, P = 4.8. 



ANALYSIS OF DATA 



In this paper I shall limit discussion of the data presented to a 

 comparison of the constants of the epiphytes among themselves and 

 with the values which have already been obtained for terrestrial forms 

 in various habitats. Even these comparisons must be limited by the 

 still unorganized condition of our data for several important habitats. 

 Since, however, it will be many months before all of these data can be 

 fully analyzed and ready for discussion, it has seemed proper to place 

 the data which have been obtained for epiphytes during the past 

 three years on record in a form which will enable other physiologists 

 and phytogeographers to use them. 



Consider first of all the relative magnitudes of the osmotic con 

 centrations found in the epiphytic plants of the two regions considered. 

 The results, grouped by families, are shown in table I. 



The constants in this table are the averages of species means, not of 

 species determinations (except when only one determination is availa 

 ble for a species), for each family. While the species means which are 

 based upon a large number of determinations are somewhat more 

 trustworthy than those which are based upon only two or three 

 readings, or upon only a single collection, the general mean for the 

 habitat is certainly more representative when calculated in this way 

 than if the habitat average had been computed directly from the 

 individual constants, thus weighting the species with the numbers of 

 collections of each which happened to be made. 



TABLE i 



Comparison of Osmotic Concentrations in Jamaican and Floridian Epiphytes 



Jamaica 



Florida 



Difference 



Bromeliaceae ;A = 0.333, P = 4.00 A = 0.464, P = 5-57 A = + 0.131, 



