180 



Dr. J. 0. W. Barratt. The Nature of the 



coagulate is markedly reduced in amount, sometimes the blood remaining 

 permanently liquid ;* in such cases the quantity of fibrin in the blood 

 vessels of the lungs is conspicuous. If, however, the amount of thrombin 

 injected is small some difficulty may be experienced in finding fibrin in 

 the pulmonary vessels, even though symptoms of illness, generally not 

 severe, have followed injection. In the viscera, other than the lungs, fibrin 

 is less readily observed and not infrequently appears to be absent. 



When the coagulant action of thrombin in vitro is compared with that 

 following upon its injection into the blood stream, it is obvious that the 

 process is essentially the same in both cases, such differences as appear being 

 due to the churning action of the circulatory movement of the blood 

 causing condensation of the delicate fibrin fibrils first formed, and thus 

 leading to the appearance of solid masses of fibrin of varying size. 



The injection of thrombokinase, contained in a suspension of the red-cell 

 stromata of the rabbit,f was effected in a series of observations carried out 

 after the following method : — 



Experiment 2. — Oxalated rabbit's blood was centrifugal]' sed until the red 

 cells were completely precipitated. After pipetting off the supernatant 

 plasma the red cells were twice washed with. 0'85-per-cent. sodium chloride 

 solution, and were then laked by the addition of an equal volume of 

 distilled water. Solid sodium chloride was then added in amount necessary 

 to form - 85 per cent, of the distilled water employed and the liquid again 

 centrifugalised, whereby the red-cell stromata were precipitated. After 

 pipetting off the supernatant solution of haemoglobin 0'85-per-cent. sodium 

 chloride solution was added in the amount required to make up the original 

 volume. The resulting liquid, which contained the red-cell stromata, 

 together with approximately half the amount of haemoglobin present before 

 laking,t served as source of thrombokinase. Of this liquid 5 c.c. were now 

 injected in the course of three minutes into the vein of the ear of a 

 rabbit weighing 1005 grm. At the end of injection the animal appeared 

 to be unaffected. Shortly afterwards, however, it became convulsed, 

 respiration failed, and death occurred at the end of 10 minutes. On 



* When this is observed, the addition of thrombin fails to produce clotting in vitro. 



t The coagulant action of a suspension of red-cell stromata upon fibrinogen in vitro 

 is exhibited in the next section (p. 185). 



% More haemoglobin may be removed from the stromata by repeated washing with 

 0'85-per-cent. sodium chloride. If this is done, larger amounts of stromata may require 

 to be injected in order to cause death. The dissolved hemoglobin does not appear to 

 give rise to any recognisable ill effect. Cp. J. O. Wakelin Barratt and W. Yorke, " tleber 

 Hamoglobinamie," ' Zeitschr. f. Immunitatsforschung u. exp. Therapie,' 1912, vol. 12, 

 p. 333. 



