1. THE PROCESS OF PREPARING BLOOD SERUM PROTEINS SUITABLE FOR USE IN DEMOSTRATING INCOMPLETE RH ANTIBODIES BY SUSPENDING REACTING BLOOD CELLS IN A SOLUTION OF THE BLOOD SERUM PROTEINS WHICH COMPRISES PASSING MAMMALIAN BLOOD SERUM THROUGH A COLUMN CONTAINING BOTH CATION AND ANION EXCHANGE RESINS IN A PROPORTION SUCH THAT A SOLUTION HAVING A PH WITHIN THE RANGE OF FROM 6 TO 8 RESULTS ON PASSAGE THROUGH THE COLUMN OF A SOLUTION SELECTED FROM THE CLASS CONSISTING OF ACIDIC, BASIC, AND NEUTRAL SOLUTIONS, WHEREBY A PRECIPITATE OF EUGLOBULINS IS FORMED IN THE SOLUTION; REMOVING THE PRECIPITATE, ADDING TO THE SOLUTION AN ALKALI METAL SALT OF AN ORGANIC ACID SELECTED FROM THE GROUP CONSISTING OF FATTY ACIDS HAVING FROM 4 TO 10 CARBON ATOMS AND ACETYLTRYPTOPHANE IN AN AMOUNT SUFFICIENT TO BRING THE MOLARITY OF THE SOLUTION WITH RESPECT THERETO TO AT LEAST ABOUT 0.15; ADJUSTING THE PH OF THE RESOLUTION TO 6.8-7.4; HEATING THE SOLUTION TO APPROXIMATELY 75* C. AND MAINTAINING THE TEMPERATURE OF THE SOLUTION A T APPROXIMATELY THIS TEMPERATURE FOR A PERIOD OF FROM 25 TO 35 MINUTES; COOLING THE SOLUTION TO A TEMPERATURE NOT GREATER THAN ABOUT 25* C.; ADJUSTING THE PH OF THE SOLUTION TO 5.5-5.8; WHEREBY A PRECIPITATE OF DENATURED GLOBULINS IS FORMED; REMOVING THE PRECIPITATED DENATURED GLOBULINS FROM THE SOLUTION; ADJUSTING THE PH OF THE SOLUTION TO 3.0-5.5, WHEREBY ALPHA-GLOBULINS ARE PRECIPITAED, COOLING THE SOLUTION TO A TEMPERATURE OF 2* TO - 1* C. AND ADDING METHANOL TO THE SOLUTION IN AN AMOUNT SUFFICIENT TO BRING THE AMOUNT WITH RESPECT THERETO TO AT LEAST 38% BY VOLUME AND AT SUCH A RATE THAT THE TEMPERATURE OF THE SOLUTION DOES NOT RISE ABOVE 2* C. DURING THE COURSE OF THE ADDITION, WHEREBY ALBUMIN IS PRECIPITATED; AND REMOVING PRECIPITATED ALPHA-GLOBULINS AND ALBUMIN FROM THE SOLUTION.