THE AGGLUTINATION REACTION 311 



Young cultures of bacteria should be employed; if grown in broth, 

 they may be prepared by rapid centrifuging and resuspension. in 

 sufficient distilled water to secure an even emulsion of such density 

 as suitable for the macroscopic agglutination test 0.3 c.c. of the 

 bacterial emulsion is placed in each of a series of small and perfectly 

 clean tubes in a rack, and 1 c.c. of the proper reaction mixture added 

 to each tube. The tubes are then gently and briefly shaken and placed 

 in a water-bath at about 37.5C. for an hour or two. Michalis 1 uses 

 acetic acid and reports sharp differentiation of Bacillus typhosus by 

 the method of acid agglutination. 



TESTS BEFORE TRANSFUSION FOR ISOHEMAGGLUTININS 

 AND ISOHEMOLYSINS 



1. Two or three c.c. of blood are obtained from each donor from a 

 vein at the elbow and 0.5 c.c. is placed at once in a centrifuge tube con- 

 taining 5 c.c. of a 1 per cent, sodium citrate in normal salt solution. 

 The remainder is placed in a small, dry test-tube until coagulation has 

 occurred and the serum has separated. 



2. From the recipient, 3 to 4 c.c. of blood are necessary; 0.5 c.c. is 

 placed in sodium citrate solution, and the remainder is allowed to coagu- 

 late and the serum collected. 



3. The sodium citrate tubes are centrifuged; the supernatant fluid 

 is pipeted off, and the cells are washed again with normal salt solution. 

 After the final washing enough normal salt solution is added to the sedi- 

 ment of cells to bring the total volume up to 5 c.c. 



4. The serum tubes are also centrifuged, so that clear serums are 

 obtained. These should preferably be free from hemoglobin stain. 



5. The following mixtures should be set up within twenty-four hours 

 of the time of collecting blood, in order that native complements may 

 not have undergone deterioration. Measurement may be made ac- 

 cording to a drop from an ordinary 1 c.c. graduated pipet held vertically. 

 Small sterile test-tubes (8 by 1 cm.) are to be used. 



Tube 1 : 4 drops of donor's serum + 1 drop of recipient's red-cell 



emulsion. 

 Tube 2: 4 drops of recipient's serum + 1 drop of donor's red-cell 



emulsion. 

 Tube 3: Control: 4 drops of donor's serum + 1 drop of donor's 



red-cell emulsion. Should show no agglutination and no hem- 



olysis. 



1 Deutsch. Med. Wchnschr., 1915, xli, 241. 



