A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

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

    85/980 page 33
    VI. In blood shed from an artery, the degree of alkalinity diminishes from the time of its being shed until coagulation is completed {Pjiiiger and Ztmtz). This is probably due to a decomposition in the blood, whereby an acid is developed, which diminishes the alkalinity (p. 1). VII. During coagulation there is a diminution of the 0 in the blood, although a similar decrease also occurs in non-coagulated blood. Traces of ammonia are also given off, which Richardson erroneously supposed to be the cause of the coagulation of the blood. [This is refuted—(1) by the fact that blood, when collected under mercury (whereby no escape of ammonia is possible), also coagulates ; and (2) by the following experiment of Lister;—He ■j)laced two ligatures on a vein containing blood, moistening oue-half of the outer surface of the vein with ammonia, leaving the other half intact. The blood coagulated in the first lialf, and not in the other, owing to the properties of the wall of the vein of the former being altered. Neither the decrease of 0 nor the evolution of ammonia seems to have any causal connection ■with the formation of fibrin.] Pathological.—When the blood coagulates within the vessels during life, the process is called thrombosis, and the coagulum or plug so formed is termed a thrombiis. AVhen a clot of blood or other body is carried by the blood-stream to another part of the vascular system where it blocks up a vessel, the plug is called an embolus, and the result embolism. 29. CAUSE OF THE COAGULATION OF BLOOD.—[Hewson's Experiments (1772.)—Hew- son tied the jugular vein of a horse between two ligatures, removed it, and then suspended it by one end (fig. 21). He found that the blood remained llaid for a long time (48 hours), the red corpuscles sank (RC) and left a clear layer of plasma on the surface (P). On drawing off some of this clear plasma it coagulated, thus proving coagulation to be due to changes in the plasma. Lister repeated this experiment, and found that, even if the upper end of the tube be opened and the blood freely exposed to the air, coagulation is but slightly hastened. He showed that the blood nuglit be poured from one vein into another, just as one might pour fluid from one test-tul)e into another. In this case there were two test-tubes, i.e., the veins—and although the blood, on being poured from the one to the other, came into contact with the air, it did not coagulate. Hewson, however, found that blood poured from the vein into a glass vessel coagulated, so that, in his opinion, the blood-vessels exerted a restraining influence on coagulation. Y>y cooling the blood and preventing it from coagulating, he proved that coagulation was not due to the loss of heat. Nor could it be a vital act, as sodic sulphate or other neutral salt j)revented coagulation indefinitely, but coagulation took place when the blood was diluted with water.] Fig. 21. [Buchanan's Researches.—The serous sacs of the body contain a fluid Vein of horse tied which in some respects closely resembles lymph. The pericardial fluid of between two lica- some animals coagulates spontaneously {e.g., in the rabbit, ox, horse, and tures. P, plasnia ; sheep) if the fluid be removed iinmediatcUj after death. If this be not WC, white, and' done till .several hours after death, the fluid does not coagulate spontane- rej cor- ously. The fluid of the tunica vaginalis of the testis sometimes accumu- puscles. lates to a great extent, and constitutes hydrocele, but this fluid shows no tendency to coagulate sjiontaneously. Andrew Buchanan found, however, that if to the fluid of ascites, pleuritic fluid, or hydrocele fluid, there be added clear blood-serum, then coagulation takes place, i.e., two fluids—neither of which shows any tendency by itself to coagulate—form a clot when they are mixed (1831). He also found, that if washed blood-clot (which consists of a mixture of fibrin and colourless corpuscles) be added to hydrocele fluid, coagulation occurred. He compared the action of washed blood-clot to tlie action of rennet in coagulating milk, and he imagined the agents which determined the coagulation to be colourless cor2}uscles. Thus, the buffy coat of horses' blood is a powerful agent, and it contains numerous colourless corpuscles. He finally concluded that some constituent in the plasma, to which he gave the name' of a soluble fibrin, is acted upon by the colourless corpuscles and converted into fibrin. The soluble fibrin of Buchanan is comparable to the fibrinogen in Hanimarsteu's theory. Buclianan, however, did not .separate the substance.] [Denis's Plasmine (1859).—Denis mixed uncoagulated blood with a s.aturated solution of .sodic sulphate, aud allowed the corj)uscles to subside. The salted plasma thus obtained he pre- cipitated with sodic chloride. The precii)itate, when washed with a saturated solution of sodic chloride, he called plasmine. If plasmine be mixed with water, it coagul{ites spontaneously, resulting in the formation of fibrin, while another proteid remains in solution. According to tlie view of Denis, fibrin is produced by tlic splitting up of plasmine into two bodies—fibrin and a soluble proteid.]
    digitised image 1
    digitised image 2
    digitised image 3