A critical and experimental essay on the circulation of the blood; especially as observed in the minute and capillary vessels of the batrachia and of fishes / By Marshall Hall.

  • Hall, Marshall, 1790-1857.
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: A critical and experimental essay on the circulation of the blood; especially as observed in the minute and capillary vessels of the batrachia and of fishes / By Marshall Hall. Source: Wellcome Collection.

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    The blood continues to flow out of these vessels for a short time; it then remains motionless in them, unless impressed by some extraneous cause. This experiment, carefully made, appears to me almost decisive of the question of the absence of irritability in the true capillaries. In order that it may succeed perfectly, it is essential that the animal should be vigorous, that the web should not be too tightly extended, and that no time should be lost in making the observations. If the circulation be feeble, or the web at all too tightly stretched, the circulation ceases entirely in all the series of vessels. Any struggles on the part of the animal must be carefully observed, and their effects distinguished from those peculiar to the experiment. The experiment of Haller and of Spallanzani consisted, not in the ligature, but in the division of the larger vessels. In such an experiment, the flow of blood is retrograde in the arteries, and thus the phenomena are complicated. The action of the heart is equally well excluded by a ligature, and the result is of a more simple and satisfactory character.