OSMOTIC PRESSURE OF TISSUE FLUIDS 
443 
VII. Dendrophthora opuntioides (L.) Eichl. 
512. On Dendropanax arboreum (L.) Dec. & PI. A = 1.13, P = 13.6 
March 18. A = i.io, P = 13.3 +0.03, + 0.3 
153. Dendropanax arborum (L.) Dec. & PI. A = 1. 16, P = 14.0 
Feb. II. A = I. II, P = 13.3 +0.05, + 0.7 
509. On Oreopanax capitatuni (Jacq.) Dec. & PI. A = 1.17, P = 14.0 
March iS.^ A = 1.53, P = 18.3 - 0.36, - 9.8 
As a basis of comparison for the individual determinations for the 
hosts, the average freezing point lowering and osmotic pressure based 
on all the determinations made, not merely those from plants on which 
parasites were found, are given in the accompanying table. 
Mean Osmotic Pressure in Sap of Hosts 
Species 
Baccharis scoparia 
Citharexylum caudatum , 
Clethra occidentalis 
Cyrilla racemiflora 
Dendropanax arboreum 
Dodonaea jamaicensis 
Duranta repens 
Eroteum theoides 
Eugenia virgultosa 
Guarea Swartzii 
Hedyosmum nutans 
Miconia guadrangularis 
Mecranium purpurascens 
Oreopanax capitatum 
Palicourea alpina 
Quercus 
Rapanea ferruginea 
Vaccinium meridionale 
Viburnum villosum 
Determi- 
Mean 
Mean 
nations 
A 
P 
3 
1. 177 
14.17 
4 
1.950 
2343 
2 
0.725 
8.75 
I 
1. 180 
14.20 
2 
1. 105 
13-30 
3 
1. 183 
14.23 
5 
1.288 
15-50 
4 
1. 143 
13-78 
I 
0.720 
8.70 
7 
0.894 
10.77 
I 
0.730 
8.80 
8 
0.988 
11.90 
2 
0.770 
9-25 
3 
1-593 
19.10 
6 
0.675 
8.12 
I 
1. 100 
13-30 
4 
1.078 
12.98 
6 
1.292 
15-55 
I 
1. 150 
13.90 
A cursory glance over the differences shows at once that in the 
great majority of the cases the freezing point lowering of the parasite 
is distinctly greater than that of the host. 
This result may be most emphatically brought out by a graphical 
representation of the constants in diagrams I and 2. In diagram i 
the amount of depression below the freezing point of pure water for 
both parasite (solid dots) and host (circles) is shown on the scale to 
the left. Here the determinations are arranged in order according 
to the freezing point lowering of the parasite. Diagram 2 is quite 
^ The young leaves of the host gave: A = 1.14, P = 13.8. 
