Carry out these procedures for both donor and recipient.

Tests: 1. In a small test-tube deposit 1 drop of the donor’s 10% red-cell emulsion and then add 4 drops of the recipient’s serum.

2. Treat similarly 1 drop of the recipient’s red-cell emulsion with 4 drops of the donor’s serum.

3. Treat 1 drop of donor’s red-cell emulsion with 4 drops of his serum.

4. Treat 1 drop of recipient’s red-cell emulsion with 4 drops of his serum. Finally add 1 cc. of salt solution to each of the four tubes, shake gently and place in incubator for two hours.

5. Treat one drop of donor’s red-cell emulsion with four drops of salt solution.

6. Treat one drop of recipient’s red-cell emulsion with four drops of salt solution.

Tubes 5 and 6 are controls of saline.

Tests 3 and 4 should fail to show either agglutination or haemolysis. If agglutination or haemolysis appears in tubes 1 or 2, the donor is not satisfactory; but if agglutination appears in tube 2 only, he may be used in an emergency.

Some prefer to keep the tubes overnight in ice-box after the preliminary examination following incubation.