American journal of physiology . re Rise from vasocon- in mm. Hg striction in mm. Hg 22 6 20 6 36 8 12 5 10 2 10 4 42 6 21 4 13 6 23 5 44 7 25 3 ^ Donaldson and Stevens: loc. cit. 2 SciiULz: Archiv fur die gesammte physiologic, 1906, cxv, p. 388. ^ Hyde: American journal of physiology, 1908-9, xxiii, p. 201. * Fucirs: Archiv fiir die gesammte physiologic, 1895, Ix, p. 189. * Greene: Bulletin of the Bureau of Fisheries, 1904, xxiv, p. 437. Vasomotor Phenomena in the Turtle 243 This particular series shows an average initial blood pressurewhich is a fraction over 23 mm. Hg, but this figure shoul
American journal of physiology . re Rise from vasocon- in mm. Hg striction in mm. Hg 22 6 20 6 36 8 12 5 10 2 10 4 42 6 21 4 13 6 23 5 44 7 25 3 ^ Donaldson and Stevens: loc. cit. 2 SciiULz: Archiv fur die gesammte physiologic, 1906, cxv, p. 388. ^ Hyde: American journal of physiology, 1908-9, xxiii, p. 201. * Fucirs: Archiv fiir die gesammte physiologic, 1895, Ix, p. 189. * Greene: Bulletin of the Bureau of Fisheries, 1904, xxiv, p. 437. Vasomotor Phenomena in the Turtle 243 This particular series shows an average initial blood pressurewhich is a fraction over 23 mm. Hg, but this figure should notbe taken to represent the average normal systemic pressure forthe turtle, because in the routine experiments the loss of bloodwas not so carefully guarded against as when blood pressurereadings alone were to be taken and therefore the figures givenare generally a little lower than they otherwise would havebeen. The strength of the stimulus was the same in all cases butthe duration varied somewhat; the stimulation was always. Figure 2. The rise in blood pressure from stimulation of the posterior splanchnicfibres. Initial pressure 32 mm. Hg. pressure 38 mm. Hg. Time linein seconds. terminated when the maximum rise in pressure had apparentlybeen obtained. The average rise in pressure from vasocon-striction indicated in this table is mm. Hg. The amountof rise in blood pressure produced by direct stimulation of thesplanchnic fibres is small as compared with that produced byadrenalin, but this difference is easily explained upon structuralgrounds. In an animal like the turtle with the splanchnic fibresso diffuse it is impossible to apply electrical stimuli effectivelyto more than a small part at one time, consequently the amountof rise in pressure will be proportionately small when comparedto a vasoconstriction produced over the entire splanchnic of stimulation of the posterior splanchnic group. —?Stimulation of the fibres which I have designated as
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