Philosophical Transactions of the Royal Society of London Volume 173, PT. 3

Philosophical Transactions of the Royal Society of London Volume 173, PT. 3

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 edition. Excerpt: ...the null point on the one side up to a height much greater than before the stimulation on the other, but also that this variation is independent of the rate of rhythm. In the majority of experiments the rhythm is seen to be decidedly accelerated by the stimulation of the nerve, in others no alteration of rhythm can be perceived. Thus in Plate 67, fig. 6, B, as soon as beats appear after the primary quiescence they show a slight acceleration of rhythm; so, too, in such figures as Plate 68, figs. 9, 10, where the nerve stimulation produced a primary diminution and a primary augmentation of the force of the contractions respectively, the rhythm is seen to be accelerated or unaltered from the commencement of the stimulation. In all cases where acceleration occurs, the return to the original rate is slow and gradual, in the same way as the return to the original contraction force. Another proof that this quiescence, which is caused by stimulation of the vagus, is not due to any interference with the rate of discharge from the motor ganglia, is most markedly shown by the fact that stimulation of the nerve often reduces the ventricle to a state of complete quiescence, while the auricles not only continue beating but beat with greater rapidity than before. Thus we may have complete quiescence of the ventricle with the auricles so nearly quiescent that their accelerated contractions are barely visible on the curve (Plate 67, fig. 7), in other cases with the auricular contractions more and more plainly visible (Plate 67, fig. 5), until finally we may obtain curves in which the ventricular beats are diminished down to complete quiescence, while the auricular are, from the commencement of the stimulation, augmented in force (Plate 67, fig. 11). The...
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Product details

  • Paperback | 146 pages
  • 189 x 246 x 8mm | 272g
  • United States
  • English
  • black & white illustrations
  • 1236888979
  • 9781236888976