THE EXAM I SAT ION OF THE BLOOD 6ii 



(2) Sheep's corpuscles washed and dihited with normal sah'ne. 



(3) vSerum in an ordinary blood tube. 



Use a throttle pipette with a long- stem and rubber teat. 



Half an inch from the capillarv end mark with a grease pencil. 



'J'his equals one volume. Permit a bubble of air and draw up 



another volume, and so on until all required are drawn up 



into the pipette. Prepare the following : — 



(i) Extract of heart muscle ... ... 4 volumes 



Syphilitic serum ... ... ... i ,, 



(2) Heart muscle 4 ,, 



Normal serum ... ... ... i ,, 



(3) Normal saline ... ... ... 4 ,, 



Syphilitic serum ... ... ... i ,, 



(4) Normal saline 4 ,, 



Normal serum i ,, 



(5) Heart muscle 4 ,, 



Incubate all these for one hour at 37*^ C. Add then to each tube one volume of 

 sheep's corpuscles. Incubate again for one-and-a-half to two hours. The results should 

 now be : — 



No haemolysis in tubes (i) and (5) 

 Haemolysis in all the others. 



The heart contains a syphilitic antigen which serves the same 

 purpose as a syphilitic foetal liver. To discuss the whole biochemical 

 process is not our purpose, but the explanation of the reactions in each 

 tube is here given in brief. 



(i) Syphilitic antigen in extract + syphilitic serum (svphilitic 

 amboceptor + complement) + sheep's corpuscles. 

 The complement is fixed, therefore there is no hcemolysis. 



(2) Syphilitic antigen + normal serum (non-specific amboceptor 



+ complement) + sheep's corpuscles. 

 The complement is not fixed, therefore hcemolysis. 



(3) Xormal saline + syphilitic serum (amboceptor + comple- 



ment) + sheep's corpuscles. 

 The complement is not fixed, therefore haemolysis. 



(4) Normal saline + normal serum (amboceptor + complement) 



+ sheep's corpuscles. 



The complement is not fixed, therefore ha?moIvsis. 



(5) Antigen + sheep's corpuscles (no amboceptor, no complement). 

 Therefore there is no haemolysis. 



THE WIDAL REACTION. 



An important diagnostic blood reaction for tvphoid and allied 

 fevers, depending upon the agglutination of the bacteria. 

 Clean the lobe of the ear with ether. 



Collect a few drops of blood in a sterile capillary tube. 

 Seal the ends in a flame with blood in tlie central part. 



