STUDIES ON THE RELATION OF THE LIVING CELLS -— 
TO TRANSPIRATION AND SAP-FLOW 
IN CYPERUS. 
JAMES BERTRAM OVERTON 
(WITH ONE FIGURE) 
Historical discussion 
Recent studies have revived with considerable vigor the doc- 
trine that the preserice of the living cells in the stem is necessary 
for the ascent of sap. The earlier evidence as to the necessity of 
living cells for sap-flow, as presented by GODLEWSKI (15) and sup- 
ported by WESTERMAIER (41, 42) and JANSE (16), was shown 
to be inadequate by STRASBURGER (30, 31) in a series of elaborate _ 
experiments, in which long portions of stems were killed with steam, _ 
hot water, and poisons, and the dead parts proved to be still 
capable of conduction. Several authors have refused to accept © 
STRASBURGER’S conclusions and have presented important criti- — 
cisms of his experimental work. 
The vitalistic theory of sap-flow, as it may perhaps be called, 
has been vigorously exploited by Ursprunc (32-37) and further _ 
supported by his student RosHarpt (24). Ursprune’s methods 
and conclusions, however, have in turn been severely criticized by _ 
Josr (17, 18), Drxon (9-12), and Czapex (7, 8). 
URSPRUNG conceives that the living cells of the stem either 
may function in keeping the vessels in a proper state for conduc- _ 
tion, or else they may take a direct part in the elevation of the sap. 
He believes that their lifting power is the more important function 
in tall plants, but that i in low herbaceous ones the living cells may 
keep the vessels in a proper condition for conductivity. In support: 
of his views he has carried out a series of experiments, in which 
portions of the petioles or stems of rooted plants were killed with 
heat, low temperature, or poisons. 
URsPRUNG’S (32) experiments were carried out on leaves of 
Primula obconica, Pelargonium zonale, Begonia sp., Impatiens Sp-» 
{28 
Botanical Gazette, vol. 51] 
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