296 BOTANICAL GAZETTE [ocroBER 
his plasmolytic studies of the plants of North African deserts and 
by ourselves in our cryoscopic determinations in the Arizona desert 
region? With an affirmative answer to this question, a second one 
concerning the closeness of agreement between the two desert 
areas so far investigated is open to discussion. 
Comparisons of the constants for sap properties here secured 
with those for other regions must be drawn with care and in only a 
preliminary fashion. This is quite obvious because of the many 
factors which may influence the constants, but concerning which 
little or no quantitative data are at present available. For example, 
the determinations for the Arizona deserts are based on collections 
made during the period of spring vegetative activity following the 
winter and spring rains; those for the coastal deserts were made 
during the dry winter season. The collections made on Long Island 
and in St. Louis at the Missouri Botanical Garden comprise decidu- 
ous species whose leaves must have developed during the spring 
of the same year. The age of the leaves of the desert plants is often 
quite indeterminable. Bearing these limitations in mind and 
remembering that there are probably many others, we note first 
of all that in a general way the flora of the Port Henderson deserts 
is in excellent agreement with that of the Tucson region in showing 
a high concentration of the tissue fluids of its constituent species. 
The exceptions only emphasize the rule. 
us comparing the Port Henderson averages for ligneous 
perennials with those tentatively drawn from unpublished data 
for trees and shrubs for the Cold Spring Harbor region," we fin 
Cold Spring Harbor, 14.40 atmospheres 
Jamaican coastal desert 
Coastal flats only, 38.81 atmospheres 
Rocky slopes only, 27.00 atmospheres 
Flats and rocky slopes, 30.05 atmospheres. 
B The averages given for both at _ ee Harbor and the Tucson series are 
by GortNer, LAWRENCE, and Harris. They will he replaced shortly by 
representing not merely determinations made in 1914 but far more extensive work ty 
abe ee and Harris in rgrs and subsequent work by Harris. The field work has 
ne for a summer series from the Arizona deserts, but the data cannot be com- 
prorat worked up for some months. 
