Vol. 51 No. 4 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
APRIL, 1924 
The Tissue Fluids of Cuscuta* 
J. ARTHUR HarRRIs 
I. INTRODUCTION 
The relationship of the phanerogamic parasite to its host pre- 
sents a group of problems of great biological interest and eco- 
nomic importance. Physiologically, one of the most interesting 
of these groups of problems is that of the relative magnitude of 
various physico-chemical constants in the parasite and host 
form, since it is upon these forces that the absorption of water and 
essential solutes may be reasonably assumed to depend. 
Earlier studies on the mistletoes have indicated that in general 
the osmotic concentration of the tissue fluids of the parasites is 
higher than that of the host plant. This has been shown for 
Viscum by plasmolytic studies by Senn (8).t It has been found 
to be the case in Jamaican Montane Rain Forest (4) and in desert 
Loranthaceae (1). The osmotic concentration of a secondary 
loranthaceous parasite has been found to be higher than that of the 
piimary parasite (2), (4). Furthermore there is evidence that 
the specific electrical conductivity, K, of the tissue fluids of desert 
mistletoes is higher than that of the host plant (5). Finally, 
it is interesting to note that in these parasites, as in terrestrial 
vegetation, the osmotic concentration is far higher in the desert 
forms than in those of the rain forest. 
* The determinations reported here were made in part in connection with 
field operations for the Office of Alkali and Drought Resistant Plant Investi- 
gations and the Office of Biophysical a of the Bureau of Plant 
Industry, U. S. Department of Agricu 
{+ Numbers refer to literature cite ot 
[The Buttetin for March (51: 83-126) was issued April 22, 1924.] 
127 
