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 449 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 
Osmotic 
Concentration 
in Atmospheres 
Orchidaceae 
Brome 
iaceae 
Jamaica 
Florida 
Jamaica 
Florida 
1. 5-1.9 
2.0-2.4 
5 
2.5-2.9 
5 
I 
2 
3-0-3-4 
I 
5 
3-5-3-9 
I 
3 
I 
4 
4.0-4.4 
I 
2 
I 
7 
4-5-4-9 
6 
I 
II 
5-0-5-4 
I 
5 
I 
14 
5-5-5-9 
I 
7 
2 
6 
6.0-6.4 
5 
7 
6.5-6.9 
2 
7-0-7-4 
I 
1 16 
30 
13 
51 
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. 
