CONDITION OF THE BLOOD 



125 



increases. The exclusion of the abdominal circulation tends to increase 

 the time of blood clotting, and if the liver circulation be eliminated, the 

 influence of epinephrin is lost. 



Hemorrhage increases the rapidity of coagulation, apparently by stimu- 

 lating the production of the fibrin factors. 



FIG. 1 08. Diagram of the Graphic Coagulometer. C, 

 In a cannula of convenient working size, 2 mm. internal 

 diameter, and 2 cm. long, which when filled with a sample 

 of fresh circulating blood is quickly plugged with wax and 

 connected by a short rubber tube with a longer glass tube 

 held in the support U. The whole is then immersed in 

 a beaker of water at constant temperature (not shown in 

 the figure). D, A copper wire of standard weight hanging 

 over the lever, the looped end is immersed in the sample of 

 blood, C. W, Counterpoising weight for the lever which 

 rotates on the axis A. S, Lever support. R X -R 2 , Short L-shaped arm which when 

 moved from P 1 to P 2 releases the lever at R 1 . To use the instrument, draw the 

 sample of blood at a signal, insert it in the apparatus, and at regular intervals release 

 the lever by moving the arm R 2 . If the blood is fluid, the counterpoising lever will 

 make a vertical stroke through its free range. If threads of fibrin have formed, these 

 counteract the movement of the lever. E, Time signal. From Cannon. 



Condition of the Blood-vessel Walls. Intravascular clotting often takes 

 place upon injury of the endothelial lining of the blood vessels, either from 

 the liberation of thrombokinase in quantity too great for elimination by the 

 healthy portion of the wall (Morawitz), or by the disturbance of the equi- 

 librium of the forces which prevent the interaction of the fibrin factors 

 present in the blood (Rettger). The healthy endothelium no doubt is an im- 

 portant factor in controlling the relative amounts of the fibrin factors that 

 must be constantly forming. The open wounds and lacerations of tissue 

 that accompany the loss of blood by accident are the very conditions most 

 favorable to clotting, since large amounts of tissue extract are set free under 

 these conditions. 



Temperature. Cold retards coagulation. Gentle warmth, 40 C., has- 

 tens, but a temperature above 56 C. destroys clotting, since that temperature 

 heat-coagulates the fibrinogen. 



Contact "with Foreign Bodies. Such contact hastens clotting. This is 

 due to the influence of such bodies in hastening the formation of fibrin 

 factors, especially the substances that arise from the disintegration of 

 leucocytes. 



Neutral Salts. The additon of neutral salts in the proportion of 2 or 3 

 per cent, and upward delays coagulation. When added in large propor- 

 tions, most of these saline substances prevent coagulation altogether. 

 Coagulation, however, ensues on dilution with water. The time during 

 which salted blood can be thus preserved in a liquid state, and coagulated 



