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Mr. M. Jantzens Theory oii the Ascent of Sap. 
A Criticism. 
Summary. 
I. The experiments of Mr. Jantzen concerning the asceiit of 
alternating columns of water and air („Jamins chains“) in wide 
tubes are more than one century old and belong to Montgolfier. 
IL Mr. J.s result, that plugs of „hard-rolled“ cotton-wool 
make but a verj slight resistance against the ascent of the chains, 
does only prove that his plugs have not been very „hard-rolled“, 
since it is certain that capillary spaces of .006 mm., inserted in a 
tube, will form a resistance corresponding to 13.6 m. of water. 
III. Mr. J.s „capillary counter-current“ does not exist; and 
in very narrow capillaires the ascending columns of water will leave 
only the adhesion-water on the walls. 
IV. The authors statement of a diiference between narrow 
glass-tubes and the tracheae of plants, in their respective resistances 
against the ascent of the chains, is incorrect. According to the 
experiments of Schwendener and others, the glass-tubes show the 
minor resistance of the two. 
The resistance of a chain is determined by the number of 
meniscuses and the resistance of each pair of these. Schwendener 
has investigated these quantities in living plants, and has found 
.that a Chain, which will resist a suction of of an atmosphere, 
must be only 2.4 m. in length. The impossibility of the ascent of 
water in trees as „Jamins chains“ or „capillary counter-current“ is 
proved by these investigations. 
V. The authors application of his theory on Angiosperms and 
Gymnosperms rests on a series of assumptions which not only are 
not proved, but are even to a great extent contradictory to well- 
established facts. Viz. 
He assumes that the transverse walls in the tracheae will act like 
his cotton - wool resistances. — They will in faet be an absolute 
hindrance to the ascent of air-bubbles. 
