A. Introduction At a meeting on psychochemicals arranged by the Battelle Memorial Institute in Columbus, Ohio, on Oct. 13, 1955, Dr. A. C. K. Elliott, of the Montreal Neurological Institute, mentioned the work of Florey. He pointed out that certain dialyzed aqueous brain extracts interfered with peripheral synaptic transmission.1One of us (H. A. A.) asked Dr. Elliott whether he knew of the reaction of Siamese fighting fish to LSD-252and suggested that it might be of great importance to study the effect of this brain extract on the reaction of fish. Upon returning to Cold Spring Harbor, a project was set up making beef brain extracts somewhat similar to those described by Florey, with modification of the process so that perchloric acid was at times omitted and lyophilization was utilized throughout. Lyophilization avoids to a certain extent the problem connected with instability in solution. It also provides