ON THE OSMOTIC CONCENTRATION OF 
THE TISSUE FLUIDS OF DESERT 
LORANTHACEAE* 
Bv J. Автнов HARRIS 
Station for Experimental Evolution 
I. INTRODUCTORY REMARKS 
In an earlier publication Mr. Lawrence and If discussed а 
series of determinations of the osmotic concentration of the tissue 
fluids of Jamaican montane rain-forest Loranthaceae parasitic 
on various hosts. The purpose of this paper is to present the 
results of studies of the sap concentration of the tissue fluids of 
desert mistletoes and of that of their host plants for comparison 
with the rain-forest series already published. 
The number of determinations upon which the conclusions of 
the present paper is based is not so large as that which Mr. 
Lawrence and I were able to obtain in Jamaica. In explanation 
I may merely say that the difficufties under which the desert 
series was secured were far greater than those which surrounded 
the work in the Blue Mountains. This has necessarily restricted 
the number of determinations, and notwithstanding our best 
* Coópera i tigati ied out under the auspices of the Department of 
Botanical be ack and the Department of Experimental Evolution, of the Carnegie 
Institution of Wash 
‘Iam seeds е ы to Mr. P. С. Standley, of the United States National 
ии for ifying these and other Arizona plants. Dr. Trelease, whose 
splendid 5 ге; the genus Phoradendron has recently EREDA pi dly 
gone over the parasites. 
Harris, J. Arthur, & Lawrence, John V. On the osmotic pressure of р tissue 
fluids of Jamaican Loranthaceae parasitic on various hosts. Am. Jour. Ж 
та 1916. 
m greatly indebted to the director and the staff of the Desert Laboratory 
for avery facility that could be given for these studies, The difficulties were such 
as are inseparable from vet idem work in camp under summer conditions in the 
Southwestern deserts. For example, the torrential rains, which are characteristic of 
the region during the midsummer season, more than once cut us off from supplies or 
facilities necessary for our wor 
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