400 BOTANICAL GAZETTE [May 
STEINBRINCK proposes** an explanation of the osmotic movement of 
water, which has the merit of substituting definite dynamics for the vague 
or ambiguous ideas of previous writers. Briefly stated he conceives the 
internal pressure of water to be reduced through the wedging apart of its 
molecules by those of the solute; the excess pressure of the pure solvent then 
determines its movement toward the region of least (internal) water pressure, 
z. é., to the points where the solution is most concentrated. As the internal 
pressure of water has been estimated at ca. 10,000 atmospheres (5,000 by 
Tumlirz), the force concerned is entirely adequate to account for any 
observed movements. e osmotic cell is thus conceived as a mechanism 
operating by differences in internal water pressure, as the pump operates by 
differences in external air pressure. The explanation has no immediat 
relation to the kinetic theory, and Steinbrinck speaks of osmotic suction, not 
osmotic pressure. This conception he expounds by clear illustrations from 
the capillary tube and the siphon, both operating on the same principle, 
though the inequalities in pressure are differently produced. He also applies 
the idea to the problem of the ascent of sap, evidently holding the cohesion 
theory as the most likely.— C. R. B 
PoLLAccl, who believes himself to have established the presence of 
formic aldehyde in green leaves (though the available tests are not beyond 
suspicion), now holds that he has materially strengthened his theory of 
photosynthesis by finding free hydrogen emitted from leaves. This, 
thinks, is set free in its nascent condition, in which it is a powerful reducing 
agent, The action normally proceeds according to the formulas: (1) 2CO, + 
2H,O = 2CH,Q3.. (2) 2CH,03;+2H,+light =CH,O+ CH,+H,0 +4 203. 
On the first step, the formation of carbonic acid, he lays considerable stress 
as an idea proposed by him. But in 18933 and repeatedly since I have 
The second formula exhibits the course of events when adequate light an 
CO, are present. But when an excess of CO, is available this formula 
becomes: (3) 2CH,O; +3H, +light = CH,0 +H,0+ 20, +CH, + H2. 
This shows Pollacci’s main result in the present memoir. But he also suggests 
an important role for nascent H in the formation of many common plant 
products. He will continue his researches, especially to determine more 
accurately the compound which some of the forms with C (appearing in 
the formula as ‘‘CH,,”’ but with probability only) and the conditions of light, 
temperature, electric charge, phase of development, etc., which influence the 
emission of free 
3 STEINBRINCK,C., Ueber dynamische Wirkungen innerer ge eciagammnem aie 
von Fliissigkeiten und ihre Beziehung zum Saftsteigproblem der Baume. Flora 93: 
127-154. 1904. 
3? POLLAcc!, GINo, Intorno all’ assimilazione chlorofillina. Memoria Il. Atti 
Istituto Bot. Univ. Pavia II. 4 
33 BARNES, C. R., On the food of green ae Bot. Gaz. 18: 405. 1893. 
