236 BOTANICAL GAZETTE [MARCH 
the principal substances which disappeared. In seeking for a catalyzer, iron and — 
manganese were considered. It was found that starch paste with traces of ferro- 
sulfate was completely hydrolyzed in six days at 100°. In a similar experiment 
without iron salts no hydrolysis took place. 
The authors conclude from their work that the fermentation of tobacco is a 
process of oxidation, in which iron salts may act as catalyzers. They believe that 
it is almost certain that the processes are of a purely chemical nature, that is, 
take place without the action of enzymes or bacteria.—H. HASSELBRING. 
Ascent of water.—Dr1xon recounts" some experiments intended to show that 
the living cells of the wood do not influence the rate at which water is transmitted 
through a stem. Arguing that if there is any sort of action which even facilitates 
the passage of water upward, its effect would be noticeable experimentally by a 
downward filtration of water more rapid in a killed stem than in a living one, he 
arranged two like shoots of syringa so that he could keep the two at the same 
temperature and could determine the amount of water that would pass downward 
through them, both being alive, under a given head of pressure in a short time, 
say 10 minutes. One shoot was then killed, by steam or by poison, with no dis- 
turbance, and the amount of water transmitted by both again determined. No 
appreciable or constant difference was found; whence Drxon argues that vital 
action is at least unlikely. 
n the basis of the strain borne by the water of a soap-bubble film, Dixon 
calculates that the tensile strength of water, even when saturated with air, is not 
less than 42.5 A, a figure which agrees fairly well with BERTHELOT’s early deter- 
mination, 50 A, to which he calls attention. In another paper,’? Drxon presents 
some further experimental work on this point. He finds a tensile strength under 
certain conditions of more than 150A. There is no longer doubt that the cohesion 
of water is sufficient to stand the strain involved in a lift; but what are the resist- 
ances to be overcome? Ewart says about 50 A; Dixon thinks this too high, 
and suggests a maximum of 20 A for the tallest trees (100™). In the absence of 
determinations of the osmotic pressure in the leaves of such trees, Drxon thinks 
it fair to assume that it is as much as 20 A. Others will en the <a 
And, as Mr. Dooley pointedly says, ‘‘There y’ are!”—C. R. 
Life of pollen.—PrunprT,?° working under the guidance of PFEFFER, has deter- 
mined the viability of pollen in air of various degrees of humidity. Incidentally 
he presents many data regarding the germination of pollen that will be useful. 
18 Dixon, H. H., Vitality and the transmission of water through the stems of plants. 
Notes from the Botany School of Trinity College 2:5-18. 1909. 
19 — Note on the tensile strength of water. Ibid. 38-43. Both “ Reprinted 
from Proc. Roy. Dublin Soc.,”’ without citation of volume or pages. 
20 Prunpt, Max, Der Einfluss der re aes auf die Lebensdauer der 
Bluthenstanbes Jahrb. Wiss. Bot. 4'7:1—40. 
