CONCENTRATION OF TISSUE FLUIDS OF EPIPHYTES 49I 
The determinations here recorded were secured in three periods of 
field work, the first in Jamaica in 191 5, the second and third in southern 
Florida in 19 16 and 191 7. In the first period I had the advantage of 
the co-operation of Mr. John V. Lawrence, who remained on the island 
for some time longer than I was able to do, and to whom I am indebted 
for a large part of the work on Jamaican forms. In the third period 
Mr. Charles W. Crane rendered most efficient service in several phases 
of the work. 
The determinations were carried out in the Tropical Laboratory at 
Cinchona, Jamaica, and in the Subtropical Laboratory of the United 
States Department of Agriculture at Miami, Florida. I have to thank 
Mr. William Harris, F.L.S., and the members of the British Association 
Committee for the use of the Laboratory at Cinchona, and am much 
indebted to Dr. David Fairchild, Agricultural Explorer, and to Mr. 
Edward Simmonds, in charge of the Plant Introduction Garden at 
Miami, for the use of the laboratory and other favors. All the species 
were determined in the herbarium of the New York Botanical Garden. 
In addition, I am indebted to Dr. Small for various courtesies in the 
field work. 
PRESENTATION OF DATA 
The following protocol gives the individual determinations for the 
several species in terms of freezing point lowering, A , corrected for 
undercooling, and osmotic concentration in atmospheres as determined 
from a published table (Harris and Gortner, 1914). The averages, 
designated by bars for each species, are given at the extreme right. 
When only a single determination is available it has of necessity served 
to represent the species in place of the average. 
In the Bromeliaceae an attempt has been made to arrange the forms 
in a rough series from the most typical tank forms to those departing 
most widely from the type in which water storage in the bases of t.he 
leaves is possible. Ultimately I hope our determinations will cover a 
range of forms sufficiently wide and be numerous enough to justify 
consideration of the problem of the relationship between sap properties 
and morphological structure in this fascinating family of plants. It 
has not seemed feasible to attempt any logical classification of the 
Orchidaceae, and they are merely alphabetically arranged for each of 
the regions. 
All the Jamaican montane rain forest determinations were made in 
1915. Hence the year is omitted when dates are cited. In the case of 
