CONCENTRATION OF TISSUE FLUIDS OF EPIPHYTES 



499 



It is clear at a glance that with the exception of the stem-succulent 

 Vanilla in the Floridian and of Octadesmia montana in the Jamaican 

 constants, the two series do not overlap in the average (generic) mag 

 nitude of their constants. With the exceptions noted, the Jamaican 

 (rain forest) genera range from 2.57 to 4.49 atmospheres, whereas the 

 Floridian genera range from 4.52 to 8. 97 atmospheres. 



Instead of limiting our comparisons between the two regions to 

 means, the individual determinations may be seriated according to 

 their magnitude and the frequency distributions compared. This has 

 the advantage of giving a general view of the range of variation in the 

 individual constants, but the disadvantage from the standpoint of 

 exact comparison that certain species are far more extensively repre 

 sented than others . The frequency distributions are given in table 3. 



TABLE 3 



Frequency Distributions of Osmotic Concentration Determinations in Jamaican and 



Floridian Epiphytes 



Because of the unusually high values found in the Spanish moss 

 (Dendropogon usneoides) it has been omitted from this table. Not 

 withstanding this fact, the Floridian Bromeliaceae as well as the 

 Orchidaceae show distinctly higher minima and maxima than the 

 Jamaican forms. The distinction between the two regions is not as 

 clearly shown by the distribution of the individual determinations as 

 by the generic means, since individual determinations must be ex 

 pected to show much wider variation than averages. 



