File:An American text-book of physiology (1897) (14803093053).jpg

Identifier: americantextbook00howe (find matches)
Title: An American text-book of physiology
Year: 1897 (1890s)
Authors: Howell, William H. (William Henry), 1860-1945 Bowditch, H. P. (Henry Pickering), 1840-1911
Subjects: Physiology
Publisher: Philadelphia : Saunders
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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mn of blood, are very incon-venient. It is essential to under-stand next the principles of themore exact instruments employedin the modern laboratory. In 1828 the French physicianand physiologist J. L. M. Poiseuilledevised means both of keeping theblood from clotting in the tubes,and of using as a measuring fluidthe heavy mercury instead of themuch lighter blood. He therebysecured a long observation, a lowcolumn, and a manageable man-ometer.^ The mercurial man-ometer of to-day is that of Poi-seuille, though modified (see Fig.100). In an improved form it con-sists of a glass tube open at bothends, and bent upon itself to theshape of the letter U. This is heldupright by an iron frame. If mer-cury be poured into one branch ofthe U, it will fill both branches toan equal height. If fluid be drivendown upon the mercury in onebranch or limb of the tube, itwill drive some of the mercury outof that limb into the other, and therest at very unequal levels. The di^ J. L. M. Poiseuille: Becherches
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Fig. 100.—Diagram of the recording mercurial man-ometer and the liymograph; the mercury is indicated indeep black: M, the manometer, connected by the leadenpipe, L, with a glass cannula tied into the proximalstump of the left common carotid artery of a dog ; A,the aorta; C, the stop-cock, by opening which the man-ometer may be made to communicate through JiT. therubber tube, with a pressure-bottle of solution of sodiumcarbonate ; F, the float of ivory and hard rubber; R, thelight steel rod, kept perpendicular by B, the steel bear-ing ; P, the glass capillary pen charged with quickly dry-ing ink ; T, a thread which is caused, by the weight of alight ring of metal suspended from it, to press the penobliquely and gently against the paper with wliicli iscovered D, the brass drum of the kymograph, whichdrum revolves in the direction of the arrow. The sup-ports of the manometer and the body and clock-workof the kymograph are omitted for the sake of simplicity.The aorta and its branches ar

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