A manual of the practice of medicine / by George Hilaro Barlow.

  • Barlow, George Hilaro, 1806-1866.
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: A manual of the practice of medicine / by George Hilaro Barlow. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    well known that tlie artificial addition of many salts to the blood retards* its coagulation, hence we may conclude that a slow coagulation may depend upon an increase of the salts. Independently, however,of these considerations, the time occupied by the coagulation appears to be influenced by the quantity of the fibrine, for if the amount of this principle be larger than ordinary, the time which elapses before the coagulation is increased, and the coagulum possesses an unusual degree of firmness: and in general, when the fibrine is abundant the clot is firm, and the coagulation slow, and when the fibrine is scanty the clot is loose and the coagulation speedy, as is the case with the last portion of the blood which flows when an animal is bled to death.* Again, it is to be remembered also that the corpuscles of the blood are of greater specific gravity than its other in- gredients, and consequently these bodies must, when the blood is at rest, have a tendency to sink towards the bottom of the vessel. This tendency is, in a great measure, counter- acted in healthy blood by the corpuscles becoming entangled in the meshes of the fibrillating fibrine forming the clot, and even then its lower portion is of a deeper colour than the upper. If, however, it happen that the blood is longer in coagulating, or the corpuscles subside more rapidly than in the healthy state, we shall have the upper part of the clot free from corpuscles or nearly so, to a greater or less depth, and forming what is familiarly known as the buff^^ coat. This network of fibrine, free from red particles, frequently continues subsequently to its coagulation, to undergo a slow contraction, by which the edges of the clot are drawn towards each other, giving its upper surface the concave appearance commonly denominated cupped. To sum up what has been said, the formation of the buffy coat is promoted, 1st, by an increase in the proportion borne by the fibrine to the red particles, whether that increase depend upon an excess of the former, or a defect of the latter; 2, by the time occupied in the coagulation of the blood, which time is increased by an increase in the salts, and an increase in the quantity of the fibrine; 3, by the rapidity with which the red particles subside through the coagulating liquid, which may be increased by a diminution of the specific gravity of the serum, and also by an arrange- * Carpenter's ' Manual of Physiology.'