The blood-pressure and its variations in the arterioles, capillaries and smaller veins / by Charles S. Roy and J. Graham Brown.

  • Roy Charles S. (Charles Smart)
Date:
[1878?]
Catalogue details

Licence: Public Domain Mark

Credit: The blood-pressure and its variations in the arterioles, capillaries and smaller veins / by Charles S. Roy and J. Graham Brown. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    Methods employed. Our observations were confined to tissues, the capillary circulation of which could be watched through the microscope. Of these, the web of the frog was preferred, as a rule, since it possesses the great ad- vantage of permitting a study of the phenomena of the blood-flow through the minute vessels without interfering to any important extent with either the general or local circulation. To control the data ob- tained, however, most of our experiments were repeated on the tongue and mesentery, of the frog and on the tails of newts and small fishes. As might have been expected, the principal facts learned are of such a nature as to leave little doubt of their general applicability to the peripheral circulation of warm-blooded animals. In Fig. 1, PI. x., is represented (somewhat diagrammatically for clearness sake, and enlarged to about twice the natural size) one of the arrangements which was employed, and which was finally found the most convenient1. In the centre of the brass plate f, measuring 10 cm. long by 4'5 broad, is screwed the small cylinder a which is closed below by the little glass plate h, the junction of which latter with the brass is made air-tight. The upper outlet of the cylinder is closed by the delicate transparent membrane d, which presses upon the web, tongue, or other part examined, when the pressure of the air within the cylinder is raised. Counter-pressure is exerted by the thin glass plate h, which is so arranged that it can be fixed at any desired height above the cylinder a. The part to be examined is placed between the cylinder and the glass plate li, which is lowered as far as is possible without causing compression of the tissue between it and the edge of the cylinder. The arrangement is shewn in the figure, g being intended to represent the web seen in section. It need scarcely be said, that the membrane which closes the little cylinder must possess certain qualities without which but little ac- curacy could be claimed for the method, (a) It must be sufficiently transparent to allow of the capillary circulation being seen clearly even with high power objectives, (h) It must be flexible enough to transmit equally to the tissue examined the pressure of the air contained within the cylinder, (c) It must be as inelastic as possible, or, at all events, its elasticity coefficient (to use a convenient but scarcely accurate term) must be considerably greater than that of the web or other tissue 1 The instrument can be supplied by Robert Fulcher, 18, Panton Street, Cambridge. 25—2