38 BOTANICAL GAZETTE [JANUARY 
sometimes in another. After 15 days a branch bearing one of the 
manometers was killed, together with a portion of the stem to 
which it was attached, by passing an induction current through 
them. After at first showing slight variations in pressure, this 
manometer followed the same periods as the others, but always 
‘“‘sucked”’ slightly more. REINDERs has given us only a preliminary 
account of his experiments, and the final report will be awaited 
with interest. 
ZIJLSTRA (43), after having kept 50 cm. of the stems of a small 
apple tree and several plants of Polygonum cuspidatum and Helian- 
thus tuberosus cooled to 0° C. 6-8 days, finds no fading of the — 
leaves during that time, while leaves on cut branches hung in the : 
neighborhood rapidly withered. In spite of this seemingly con- 
vincing result, he still believes that the living cells are necessary 
to sap-flow, as held by his associate REINDERS. His explanation 
is that it is quite probable that 50 cm. is too short a stretch to © 
show conclusive results, although he did not take the trouble to_ 
treat longer portions. Both of these investigators, therefore, — 
advocate the doctrine of a pumping action of the wood, as formu- 
lated by GoptEwsk1, for which the living cells-are necessary. — 
Z1JLsTRA allowed a solution of “‘siure violett”’ to ascend dead and 
living branches, and then examined them microscopically. In the 
living ones only the tori of the bordered pits were stained, together 
with a thin layer of the walls of the vessels. In the dead branches — 
the whole of the wood was uniformly colored. He concludes, 
therefore, that the ascending water takes quite a different course 
in dead wood from that in living wood. 
Jost (17, 18) points out that Ursprunc’s method of experimen: : 
tation is an indirect one, and that, if it is not due to an increased - 
evaporation in the scalded portion or to the stoppage of the vessels, ; 
which URSPRUNG was unable to find, then it must be due to the 2 
death of the parenchyma cells. He suggests that by heating the 
stem perhaps changes occur in the walls or in the contents of the 
vessels which one cannot readily observe with the microscope. 
CzAPEK (7, 8) also doubts the worth of such experiments 4 
described by UrsPRUNG, since in the killed portion physical disturb-_ 
ances may be induced, such as drying out of the cells walls or 
