PRACTICAL EXERCISES 57 



from the corpuscles in a, /9, and 7, and also from the peptone 

 blood. 



With the oxalate plasma from j3, and the fluoride plasma from y, 

 repeat the observations in (8) and (9), using smaller quantities of 

 the plasma, if necessary, in small test-tubes. With the plasma from 

 a perform the following experiments : Put a small quantity of the 



lasma (i c.c.) into four test-tubes, labelling them ' Magnesium 

 ulphate A, B, C, D.' Dilute B with four times, C with eight times, 

 and D with twenty times as much distilled water as was taken of 

 the plasma. Observe in which, if any, coagulation occurs, and the 

 time of its occurrence, and report the result. 



(u) With peptone plasma from H and from the peptone blood 

 obtained later repeat the experiments done in (7). In addition 

 dilute i c.c. of the plasma with three volumes of water and i c.c. 

 of it with ten volumes of water, and put in the bath at 40 C. Observe 

 whether clotting occurs. 



If no centrifuge is available, the various blood-mixtures must be 

 left standing in a cool place for 12 to 24 hours till the corpuscles 

 settle. The plasma can then be siphoned or pipetted off. Instead 

 of dog's blood, the blood of an ox or pig may be obtained at the 

 slaughter-house. 



4. Preparation of Schmidt's Fibrin-ferment. Precipitate blood- 

 serum with ten times its volume of alcohol. Let it stand for several 

 weeks, then extract the precipitate with water. The water dissolves 

 out the fibrin-ferment, but not the coagulated serum proteins. 



5. Preparation of Tissue Extracts containing Thrpmbokinase. 

 In a dog or rabbit killed by bleeding insert a cannula into the lower 

 end of the thoracic aorta. Fill the cannula with 0-9 per cent, salt 

 solution or water, and connect it with a bottle also containing salt 

 solution or water. Wash out the vessels of the lower portion of 

 the body, making an opening in the inferior vena cava above the 

 diaphragm to allow the liquid to escape. For the sake of cleanli- 

 ness, a cannula armed with a piece of rubber tubing should be 

 inserted for this purpose into the inferior vena cava. Continue 

 the injection till the liquid issues colourless. Then remove portions 

 of liver and muscle. Mince each separately. Rub up with sand in 

 a mortar. Add 0*9 per cent, sodium chloride solution and rub up 

 again. Put into bottles and keep in the ice-chest. For use take 

 off some of the liquid from the top with a pipette, or strain through 

 cheese-cloth. 



6. Serum. Test the reaction, and determine, both by the hydro- 

 meter and the pycnometer, or specific gravity bottle, the specific 

 gravity of the serum provided, or of the serum obtained in experi- 

 ment 3. 



Serum Proteins. (i) Saturate serum with magnesium sulphate 

 crystals at 30 C. The serum-globulin is precipitated. Filter off. 

 Wash the precipitate on the filter with a saturated solution of mag- 

 nesium sulphate. Dissolve the precipitate by the addition of a 

 little distilled water, and perform the following tests for globulins : 

 (a) Saturate with magnesium sulphate. A precipitate is obtained. 

 (6) Drop into a large quantity of water, and a flocculent precipitate 

 falls down, (c) Heat. Coagulation occurs. Determine the tempera- 

 ture of coagulation (p. 8). 



(2) To a portion of the filtrate from (i) add sodium sulphate to 

 saturation. The serum-albumin is precipitated. (Neither mag- 

 nesium sulphate nor sodium sulphate precipitates serum-albumin 



