106 



EXERCISE XVII 



Obs. 79. 

 Haemorrhage 

 and arterial 

 pressure. 



VIII. Returning to femoral artery, tie the distal ligature and, controlling 

 the artery by weighting the proximal looped thread, insert the arterial cannula 

 provided with rubber tubing into the femoral artery, nozzle towards the heart. 

 Secure cannula by tying middle ligature. Restart the kymograph. Bring 

 glass beaker to the cannula and, releasing the femoral artery from the 

 weighted proximal thread, allow about 30 c.c. blood to flow into beaker. 

 Note effect on the pressure record. Stop the kymograph. Stir the blood in 

 the beaker with the glass rod to defibrinate it. Set the whipped blood to 

 stand and sediment. 



IX. Draw off into the small evaporating- dish about 10 c.c. of blood from 

 femoral and set it aside. 



Obs. 80. 

 Bestoration of 

 art. pressure by 

 gum-saline 

 injection. 



Obs. 81. 

 Retardation of 

 clotting by 

 ' decalcifica- 

 tion '. 



Obs. 82. 

 Fibrinogen in 

 plasma and not 

 in serum. 



X. Similarly draw off into each of the centrifuge-tubes enough blood 

 to half fiU it, and at once mix the blood and pot. oxal. solution, by 

 inverting once ; avoid shaking and frothing. Set to stand. 



Measure up approximately the total quantity of blood withdrawn in 

 §§ VIII, IX, and X, and measure out a quantity of the gum-saline equal 

 to the blood withdrawn. 



XI. Note the arterial pressure. Inject through the femoral cannula 

 with the syringe the measured quantity of gum-saline fluid. Inject it warmed 

 to 38° C. Observe effect on carotid pressure. 



XII. Note that the blood has not clotted in the tubes containing 

 pot. oxalate, but has clotted in the other test-tubes. Before centrifuging, 

 make the quantity of blood in the several centrifuge-tubes equal by pouring 

 from one into another. Centrifuge the blood. Note the plasma and the 

 leucocyte layer on the top of the red corpuscle sediment. 



XIII. Pipette off the plasma from the centrifuged tubes and place some 

 in two test-tubes, A and B. Pipette off some of the serum from the whipped 

 blood which has been standing, and place some in two test-tubes, C and D. 

 To two of these, A and C, add an equal volume of saturated NaCl solution. 

 Mix and note clot-like ppt. (fibrinogen) in A but not in C. Place the other 

 tubes, B and D, in the water-bath and raise temperature slowly ; note heat-ppt. 

 in B at about 58° C, but not in D until about 72° C. 



XIV. Return to carotid-pressure record ; note the amount of restoration 

 of the pressure which the gum-saline injection has maintained. 



