OSMOTIC CONCENTRATION OF TISSUE FLUIDS 
291 
The relative differences are not large. In only a single comparison 
does the ratio indicate a difference of as much as 23 percent. 
Table V shows that the concentration in the plants of the leeward 
ravines is lower than in those of the ruinate or of the ridge forest 
Table V 
Growth Form 
Leeward 
Ravines 
Leeward Ravines Compared with Other Habitats 
Ruinate of 
Leeward Slopes 
Ridge Forest 
Windward 
Slopes 
and Ravines 
All Habitats 
Herbaceous .... 
7-59 
-2.18 
— 1.04 
+ 0.07 
— 1. 21 
1. 00 
0.78 
0.88 
I.OI 
0.86 
10.83 
— 2.22 
-0.71 
+ I.IO 
— 0.61 
All species 
1. 00 
0.83 
0.94 
I. II 
0.95 
9.89 
-2.18 
— 1. 12 
+0-93 
— 0.70 
1. 00 
0.82 
0.90 
1. 10 
0.93 
but higher than that of the windward slopes and ravines. The dif- 
ferences between the concentrations in the leeward ravines and on the 
ridges on the one hand and between the leeward ravines and the 
windward ravines on the other are not large. 
The final comparison is that of the windward ravines and slopes 
with the other habitats. This is made in Table VI. The differences 
show that the plants of the most hygrophytic habitat of the region 
Table VI 
Growth Form 
Windward 
Slopes and 
Ravines 
Windward Slopes and Ravines Compared with Other Habitats 
Ruinate of 
Leeward Slopes 
Leeward 
Ravines 
Ridge Forest 
All Habitats 
Herbaceous .... 
7.52 
-2.25 
— 0.07 
— I. II 
-1.28 
1. 00 
0.77 
0.99 
0.87 
0.85 
9-73 
-3.32 
— 1. 10 
-1. 81 
-I.7I 
All species 
1. 00 
0.75 
0.90 
0.84 
0.85 
8.96 
-3-II 
-0.93 
-2.05 
-1.63 
1. 00 
0.74 
0.91 
0.81 
0.85 
under investigation are characterized by a lower osmotic concentra- 
tion than those of any other habitat. To this rule there is not a 
single exception. The values range from 74 to 99 percent of that 
of other habitats. 
Comparison of Blue Mountain Rain Forest with Other Regions. — 
Our work in Jamaica was undertaken primarily to secure determina- 
tions from an extremely hygrophytic habitat for comparison with the 
