Directions for a practical course in chemical physiology / W. Cramer.

  • Cramer, William, 1878-1945.
Date:
1917
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Licence: In copyright

Credit: Directions for a practical course in chemical physiology / W. Cramer. Source: Wellcome Collection.

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    appears. (For further investigation of proteins of serums see Experiments 85, 86.) Separate the fibrinogen precipitate from the plasma by centrifugalising, decant the supernatant fluid. Wash the precipitate with a half-saturated solution of NaCl (in which it is insoluble), and dissolve it in 10 c.c. of a 0-9 per cent. NaCl solution. Label “ Fibrinogen Solution.” With a little of the fibrinogen solution perform biuret test and heat coagulation test for proteins. Both are positive. Label four test tubes E, F, G, H; charge with the various solutions, and place in water-bath kept at 35°. Tube. Contents of Tubes. Result. E 1 c.c. fibrinogen solution + 02 c.c. CaCl9 - No clot. F 1 c.c. fibrinogen solution+ 0'2 c.c. CaCl2 + 0‘2 c.c. platelet extract ..... Clot. G 1 c.c. fibrinogen solution+0‘2 c.c. CaClo tO'2 c.c. serum ------- Clot. H 1 c.c. fibrinogen solution + 0‘2 c.c. CaCL + 0'2 c.c. plasma, filtered ----- No clot. These experiments show :— 1. That the protein precipitated from plasma by half saturation with NaCl is the third constituent concerned in the formation of a blood clot. 2. That this protein when acted upon in the presence of soluble calcium salts by the coagulating agent present in the platelets gives rise to fibrin (tube F). 3. That this protein (fibrinogen) is absent from serum. 4. That the coagulating agent remains active after the clot has been formed, i.e., it is present in serum (tube G). It is absent from plasma (tube H). From these experiments the main facts of the process of blood coagulation can be tabulated as follows:—
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