. An introduction to vegetable physiology. Plant physiology. TKANSPIEATION 105 It is, however, very sensitive to slight changes in the environment. It was mentioned in an earUer part of this chapter that the force of transpiration is of considerable assistance in maintaining the upward flow of water from the roots. The apparatus shown in fig. 69 enables this to be demon- strated. The cut end of a branch is connected by an air-tight joint with a glass tube filled with water, the lower end of which dips into a vessel of mercury. As the water is transpired, a certain quantity of mercury enters th
. An introduction to vegetable physiology. Plant physiology. TKANSPIEATION 105 It is, however, very sensitive to slight changes in the environment. It was mentioned in an earUer part of this chapter that the force of transpiration is of considerable assistance in maintaining the upward flow of water from the roots. The apparatus shown in fig. 69 enables this to be demon- strated. The cut end of a branch is connected by an air-tight joint with a glass tube filled with water, the lower end of which dips into a vessel of mercury. As the water is transpired, a certain quantity of mercury enters the tube, and is drawn up for some considerable distance by the suction. The evaporation from the cells takes place, as we have seen, not immediately into th;B external air, but into the intercellular passages of the plant. The force causing this suction, so far as it is due to evaporation, is there- fore localised in the surface film formed in the evapo- rating cell-walls. Such an evaporation has been shown by Strasburger to be capable of raising a current of water through pieces of dead wood which have been soaked and injected with water. Osmosis in the Leaves.—There is reason to believe, however, that a third factor in the ascent of the stream is. Fm. 69.—Appaeatus to show the Suction caused by Tbanspiea- TION. (After Detmer.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Green, J. Reynolds (Joseph Reynolds), 1848-1914. London, J. & A. Churchill
Size: 1002px × 2495px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondonjachurchill
