A quick method of performing the Paul-Bunnell test.

(4) In the remaining tubes of each row is placed 0.5 ml. of 0.85% sodium chloride. (5) To the first tube of each row 0.1 ml. of serum is added and mixed thoroughly. (6) Then 0.5 ml. of the diluted serum is carried over into tube 2 and so on until tube 10, the last 0.5 ml. being discarded. (7) To each tube 0.5 ml. of washed fresh sheep cells is added, thus giving a final serum dilution of 1:20 up to 10,240. (8) One row of tubes is now placed in a separate rack. The separate rows of tubes are now treated as follows: A. Orthodox Technique.-One rack is incubated at 370 C. for four hours, after which it is stored overnight in the refrigerator at 2 to 40 C. The following morning the rack of tubes is re-incubated at 370 C. for one hour, after which macroscopic agglutination is looked for after gently inverting the tubes twice.