OSMOTIC CONCENTRATION OF TISSUE FLUIDS 289 
habitats in the rain-forest region the comparison of each of the four 
habitats with the three others may be made in detail in a series of 
four tables. 
In view of the differentiation between herbaceous and ligneous 
plants demonstrated above, the comparison must first be made for 
each class separately. 
In these tables each of which is devoted to the values showing 
the absolute and relative magnitudes of the constants of a given 
habitat, the comparisons are made in two ways. First, the actual 
differences in mean osmotic concentration, P, between any habitat 
and the three other habitats have been determined. These are the 
values with signs. Second, the ratio of the mean osmotic concentra- 
tion of the sap of every habitat to that of each other habitat with 
which it is to be compared has been determined. These are the values 
given in black-faced type. 
The first method has the obvious advantage that differences are 
expressed in the concrete terms of osmotic concentration. Relative 
values, as employed in the second method, are on the other hand 
more convenient for comparison. The exact method of drawing the 
comparisons will be clear from an explanation of the individual 
tables. 
The first column of Table III, in which the values obtained in the 
Table III 
Growth Form 
Ruinate of the 
Leeward Slopes 
Ruinate of the Leeward Slopes Compared with Other Habitats 
Leeward 
Ravines 
Ridge Forest 
Windward 
Slopes and 
Ravines 
All Habitats 
Herbaceous .... 
9-77 
+ 2.18 
+ I.I4 
+ 2.25 
+ 0.97 
Ligneous 
1. 00 
1.29 
1.30 
I. II 
13-05 
+ 2.22 
+ I-5I 
+3-32 
+ I.6I 
1. 00 
1.20 
1. 13 
1-34 
1. 14 
All species 
12.07 
+ 2.18 
+ 1.06 
+3-II 
+ 148 
1. 00 
1.22 
1. 10 
1.35 
1. 14 
ruinate of the leeward slopes are compared with those of each of the 
other habitats, gives the growth forms on which the comparisons are 
based. It has been practicable to recognize only two of these in the 
Blue Mountain region, the herbs and arborescent, frutescent and 
suffrutescent plants. The second column gives the actual mean 
values in atmospheres of the plants of the ruinate. The third to 
