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

  • Landois, Leonard
Date:
1888
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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.

    86/980 page 34
    [A. Schmidt's Eesearches (1861).—This observer rediscovereil the cliief facts aheaily known to Buchanan, viz., that some Huids which do not coagulate siiontaneously, clot when mixed with other fluids which show no tendency to coagulate spontaneously, c.cj., hydrocele lluid and blood-serum. He isolated Ironi these fluids the bodies described as hbrinogeu and fibrino- plaslin. The bodies so obtained were not pure, but Schmidt sujjposed that the formation of librin was due to the interaction of these two proteids. The reason hydrocele lluid does not coao-ulate, he says, is that it contains fibrinogen and no fibrino-plastin, while blood-serum con- tains the latter, but not the former. Schmidt afterwards discovered that these two substances may be present in a fluid, and yet coagulation may not occur {e.g., occasionall}- in hydrocele fluiil). He su]'posed, therefore, that blood or blood-serum contained some other constituent necessary for coagulation. This lie afterwards isolated in an ini[)ure condition and called fibrin-fcrment.'\ A. Schmidt's theory is that fibrin i.s formed by the coming together of ttio proieid siibstancL's wliicli occur di.ssolved in the plasma, viz.:—(1) fibrinogei?; i.e., the substance which yields the chief mass of the librin, and (2) fibrino-plastic substance or fibrino-plastin (serum-globulin or paraglobulin, § 32). In order to determine the coagulation a fernient seems to be necessary, and this is supplied hy (3) the fibrin-ferment. 1. Properties.—Fibrinogen and fibrino-plastin belong to the group of proteid.s called globulins, i.e., they are insoluble in pure water, but are soluble in dilute solutions of common salt (§ 249), and are not distinguished from each other by well- marked chemical characters. Still they differ as follows :— Fibrino-plastin is more easily precipitated from its solutions than fibrinogen. It is more readily redissolved when once it is precipitated. It forms when pre- cipitated a very light granular [)Owder. Fibrinogen adheres as a sticky deposit to the side of the vessel. It coagulates at 56° C. On account of their great similarity, both substances are not usually prepared from blood-plasma. Fibrinogen is prepared from serous transudations (pericardial, abdominal, or pleuritic fiuid, or the fluid of hydrocele), which contain no fibrino- plastin. Fil>rino-plasti?i is most readily prepared from serum, in which there is still plenty of fibrino-plastin, but no fibrinogen. 2. Preparation of Fibrino-plastin, Serum-globulin, or Paraglobulin.—(«) Dilute blood-serum with twelve times its volume of ice-cold water, and almost neutralise it with acetic acid [add 4 drops of a 25 per cent, solution of acetic acid to every 120 c.c. of diluted serum] ; or (b) pass a stream of carbon dioxide through the diluted serum, which soon becomes turbid ; after a time a fine white powder, copious and granular, is precipitated. [(c) Method of Hammarsten.—All the fibrino-plastin in serum is not precipitated either by adding acetic acid or by CO.,. Hammarsten found, however, that if crystals of magnesium sulphate be added to complete saturation, it precipitates the whole of the serum-globulin, but does not precipitate serum-albumin; serum-globulin is more abundant than seruin-albumin in the serum of the ox and horse, while in man and the rabbit the reverse obtains ; (compare § 32).] Schmidt found that 100 c.c. of the serum of ox blood yielded 07 to 0-8 grni. ; horse's serum, 0-3 to 0-56 grm. of dry fibrino-plastin. Fibrino-plastin occurs not only in serum, but also in red blood-corpuscles, in the fiuitls of connecti)-e-tissue, and in the juices of the cornea. 3. Preparation of Fibrinogen.—This is best prepared from hydrocele fluid, although it may also be obtained from the fluids of serous cavities, e.g., the pleura, pericardium, or peritoneum. It does not exist in blood-serum, although it does exist in blood-plasma, lymph, and chyle, from which it may be obtained by a stream of CO^, after the paraglobulin is precipitated, (a) Dilute hydrocele fiuid with ten to fifteen times its volume of water, and pass a stream of CO^ through it for a long time, (b) Add powdered common salt to saturation to a serous trans- udation, when a sticky glutinous (not very abundant) precipitate of fibrinogen is> obtained.
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