A comparison of brain thromboplastin preparations used for testing prothrombin efficiency.

Methods 1. Quick's Method.-The method in use in this laboratory has been basically that of Quick, StanleyBrown, and Bancroft (1935), as modified later by Quick himself and others (Biggs and Macfarlane, 1949). In this method a fresh saline emulsion is prepared daily from a stock of acetone-dried human brain powder, which is kept stored in a vacuum desiccator at 40 C. 2. Toohey's Method.-This method obviates the necessity of using dried brain extracts (Toohey, 1941, 1950; Owen and Toohey, 1941). Fresh human brain stripped of membranes and blood vessels is simply macerated with 0.5% w/v phenol in 0.85% w/v saline. The emulsion is thoroughly shaken and kept in a tightly stoppered container at 40 C. In