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Societies and Academies

    Naturevolume 105pages410411 (1920) | Download Citation

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    Abstract

    LONDON. Royal Society, May 13.—Sir J. J. Thomson, president, in the chair.—Dr. A. D. Waller: Demonstration of the apparent “growth” of plants (and of inanimate materials) and of their apparent “contractility.” In Sir J. C. Bose's original demonstration an amputated leaf was fixed up in connection with a crescograph, at a magnification stated to be × 107, and the indicator was shown to be moving in a direction and at a speed that were stated as representing the growth of the petiole. Alternating currents were now sent through the leaf, causing a sudden reversal of the movement of the indicator, e.g. in the demonstration that the present author witnessed at the Royal Society of Medicine the indicator (a spot of reflected light) moved to the right at what he judged to be something like 1 metre per sec. in the direction of elongation (by growth?), and flew off scale in the opposite direction, at least ten times as fast, as soon as the buzz of the exciting coil was heard (“degrowth”). The demonstration was, in Dr. Waller's opinion, illusory. The movement to the right (indicating an elongation of petiole = 0.1 m. per sec.) was indeed consistent with “growth,” although its rate was surprisingly high under the conditions of experiment. The elongation might, however, have been due to, or modified by, many accidental variations of conditions—heat, moisture, handling of plant during preparation, etc.—and was precisely similar to the gradual elongation that takes place in a damp fiddle-string under similar conditions. The second part of the experiment, when the “excited” plant shortened and caused the indicator to fly off to the left, is held to afford conclusive proof of fallacy. The fact belonged to the familiar phenomena of heat contraction aroused by electrical currents in all kinds of (doubly refracting) moist conductors, whether living or dead, to the study of whicn attention was directed by Engelmann in his Croonian Lecture of 1895. These are demonstrable with a low-power crescograph (× 103), and play a part in masking or simulating phvsiological changes when a high power (× 107) is employed.—W. N. F. Woodland: The “renal portal” svstem (renal venous mesh work) and kidnev excretion in vertebrata. The first three Darts of this memoir contain, in the first place, proof that the assumption, commonly made in phvsiological literature, that the venous blood “supplied” to the kidneys of lower vertebrata mixes with the arterial blood and traverses the system of channels known in mammals as the intertubular plexus, is erroneous—the renal afferent vein-blood does not supply the kidney tubules. The renal artery-blood traverses the intertubular plexus proper, and the renal afferent vein-blood a system of wide sinusoids (renal venous mesh work), which has no connection with the intertubular plexus, save that the latter opens into the former where the venous blood flows into the renal efferent veins. In the second place, much experimental and otherevidence is provided to prove that the “renal portal” system is devoid of function so far as kidney secretion is concerned. Evidence is also adduced to show that the urine is solely secreted by the renal tubules, the glomeruli taking no part. The glomeruli (as will be explained in the forthcoming Part iv.) are solely to be regarded as retia mirabilia and function as such. This is the tubule-cum-rete theory of kidney secretion.

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    https://doi.org/10.1038/105410a0

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