Page:The third Huxley lecture.pdf/54

50 the other constituent being derived from the blood-corpuscles. The ordinary solid, therefore, in determining coagulation, does not cause the deposition of fibrin already formed, but so influences the corpuscles as to make them give up an ingredient necessary for the formation of that insoluble body.

With this further light upon the subject, the conclusions derived from the experiments to which I have referred seem to explain the special coagulability of the exudation in intense inflammation. Under intense irritation the capillary walls will naturally be affected by the noxious agency as the veins of the sheep's foot were by the constricting cord, and, like them, will act upon their contained blood as if they were ordinary solids. The plasma of that blood will therefore receive from the blood-corpuscles the material requisite for forming fibrin, and, passing through the pores of the capillaries with that addition, will constitute a coagulable exudation.

On the other hand, if irritation is less severe, although the corpuscles acquire more or less adhesiveness, involving corresponding obstruction to the flow through the capillaries and consequent undue passage of liquor sanguinis through their walls, the