1906] CURRENT LITERATURE I51 
the maintenance of normal conditions in the conducting tissues. Then UrspruNG 
5b 
rallied to the support of SCHWENDENER with experimental work, and in a paper 
published two years ago® contended that the living cells, either by maintaining 
the conducting system in condition or by actually lifting, had an important share 
in the ascent of water. His experiments were carried out on small plants mainly, 
and he ventured no generalization. 
In a more recent paper’® he reviews critically the direct and incidental experi- 
ments of others on this subject, replies to objections raised against his earlier 
paper; and details further experiments intended to ascertain the precise rdle of 
living cells. The author adopts a rather hypercritical attitude toward previous 
results, as is well illustrated by this reasoning regarding girdling: ‘‘If at the 
base girdling 14m Jong is borne without injury, it does not signify that this would 
be the case also at the apex; and if girdling 14™ long does not interrupt the 
conduction of water, it is not proved that this would not occur with girdling one 
or two meters long. Hence it follows that the bark (Rinde) must be entirely 
temoved if one wishes to form a judgment as to its share in the ascent of sap; 
and even then one can at most only recognize that it may be dispensed with— 
not that under ordinary conditions it takes no part in the ascent of sap.” 
By liberal discounts Ursprunc arrives at the conclusion that all previous 
researches on this point speak in favor of the participation of living cells in rais- 
mg water. Even the experiments of SrRASBURGER, which have been interpreted 
as flatl¢ contradictory to such an idea, are counted as offset by his finding that 
the leaves die after one actually kills 10° of the stem. For, according to UrR- 
SPRUNG, the cooperation of living cells throughout the entire length of the plant 
1S Necessary; but a small fraction of the conducting system suffices to supply 
Water if in this region the wood cells are living; whereas the whole is inadequate 
to furnish enough water when they are killed. These living cells do not merely 
keep the conducting tissues in good condition; they ‘cooperate in the production 
of the lifting force,” and the component which they furnish is of great significance 
i comparison with the “purely physical.’’ A notable exception is the beech, in 
Whose older parts the cells of the bark are without influence, “‘and even in the 
youngest parts such interaction is insignificant.” It is hard to conceive how 
the living cells in the bark, being outside the water paths, can participate in the 
work of raising water, and harder still to imagine that they do so in certain plants 
and not in others, 
STEINBRINCK attacks the problem from the ‘purely physical” side,** and 
— As, Untersuchungen iiber die Beteiligung lebender Zellen am Saft- 
- Beihefte Bot. Cent. 18:145-158. 1904. 
Mice Die Beteiligung lebender Zellen am Saftsteigen. Jahrb. 
* 42:503-544.- 1906, 
*t STEINBRINCK, C. Untersuchung iiber die Kohiasion strémender Flussigkeiten 
5 Wi 
. te auf das Saftsteigeproblem der Baume. Jahrb. Wiss. Bot. 42:579- 
5+ 1906, 
