Researches on irritability of plants

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Longmans, Green, and Company, 1913 - 376 pages

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Page 7 - B. pull exerted by the motile organ is relatively feeble, and in the movement of the very small leaflets of Desmodium gyrans or the telegraph plant, for instance, a weight so small as four-hundredths of a gram is enough to arrest the pulsation of the leaflets. Even in the leaf of Mimosa the friction offered is enough to introduce serious errors into the amplitude and time relations of the curve. This error could not be removed as long as the writer remained in continuous contact with the writing...
Page 155 - I find it extremely difficult to be sure of killing the interior of a tissue by scalding the outside. This derives additional support from certain experiments of Kuhne on conduction of excitation in a nerve, the specimen employed being the sartorius of a frog. ' The delicate nerve which enters the middle of the sartorius by one side, divides within the muscle so that the single fibres that constitute the bifurcation branch many times dichotomously. When Kuhne threw the broad upper end of the muscle...
Page xxiii - In its apparent immobility and placidity the plant stands in strong contrast to the energetic animal with its reflex movements and pulsating organs. Yet the same environment which, with its changing influences, so profoundly affects the animal, is also playing upon the plant. Storm and sunshine, the warmth of summer and the frost of winter, drought and rain — all these and many more come and go about it. What subtle...
Page 15 - S', screw foradjustmcnt of distance of writing-point from recording plate. S, screw for vertical adjustment. T, tangent screw for exact adjustment of plane of movement of recorder, parallel to writing surface.
Page vii - ... case, as in the other, the tremor of excitation is transmitted with a definite and measured speed from point to point along conducting channels. The establishment of this similarity of responsive actions in the plant and animal will be found of the highest significance; for we now realize that it is by the study of the simpler phenomena of irritability in the vegetal organisms that we may expect to elucidate the more complex physiological reactions of the animal. THE PLANT'S RESPONSE TO THE SHOCK...
Page 107 - ... muscle of a frog the latent period, according to Helmholtz, is about a hundredth part of a second. This result is not without some error, on account of the inertia of the recording lever, and the inferring of time relations from a neighboring chronographic record. In my resonant recorder these errors have been reduced to a minimum. In the first place, the curve of response or phytogram is at the same time a chronogram.
Page 171 - Abolition of conduction by local application of potassium cyanide. (1) Normal record; (2) arrest of conduction after application for five minutes; (3) persistent abolition of conduction, even when stimulus was Increased fifteen-fold; (4) record of direct stimulation.
Page 1 - The swollen mass on the lower side is very conspicuous. Under excitation, the parenchyma in this more effective lower half undergoes contraction, in consequence of which there is a fall of the leaf. This sudden movement constitutes the mechanical response of the leaf to the impinging stimulus, just as the contractile movement of a muscle in similar circumstances forms its characteristic mechanical response.
Page 5 - This error could not be removed as long as the writer remained in continuous contact with the writing surface. I was, however, able to overcome this difficulty by making an intermittent, instead of a continuous, contact. The possibility of this lay in rendering the Fio. 2.— Response curve of primary leaf of Mimosa. The vertical lines below the record indicate Intervals of one minute each. writer tremulous. Fresh difficulties arose which were finally eliminated by an invention depending on the phenomenon...

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