The vaso-motor system / by Sir William M. Bayliss.

  • William Bayliss
Date:
1923
Catalogue details

Licence: In copyright

Credit: The vaso-motor system / by Sir William M. Bayliss. Source: Wellcome Collection.

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    of the eight seconds and of twenty seconds closure of the artery. Recent experiments with isolated arteries have shown me that it is very difficult to obtain one that is capable of stimulation either by chemical or electrical means, so that the failure of distension to produce a con¬ traction in the experiments of this kind done by Anrep is not a serious objection. It may be pointed out that if the asphyxia theory is not a satisfactory explanation for the case of the reaction to decrease of internal pressure, it follows that the vessel was previously in a state of con¬ traction owing to distension. On the whole, I fear that we must regard the question as undecided. THE “PERIPHERAL HEART THEORY. Connected with the problem of the preceding paragraph is the view put forward by Hurthle (1912, 1913) that the blood is assisted onwards by a contraction of the arteries behind each pulse wave. It was found that the rate of flow through an artery was, in certain conditions, greater than could be brought about by the mere difference of pressure between its ends. The amplitude of the pulse wave was also found to be increased as it passed onwards in the living animal, as contrasted with its behaviour in the dead one, where it decreased in the way that would be expected. The interpretation of these facts is difficult and Hess (1916) has subjected the theory of the “peripheral heart” to a severe criticism, pointing out that such a con¬ traction of the artery would be effective only if it were great enough to close the lumen entirely. On the other hand, Carl Tigerstedt (1913) found that if two electrodes were placed on the carotid artery there was an electrical response of the arterial muscle to each heart beat, of such direction as to indicate the progression of a wave of con-
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