The diagnosis of syphilis, and especially of latent syphilis, has become a matter of increasing importance in mental hospital practice. The great difficulty hitherto experienced has been in connection with the adoption of some routine laboratory test. As long as the Wassermann was the only serological test available, many institutions were confronted with the task of undertaking a test that was too complex and difficult for all but the best equipped laboratories. This is now so well recognized that it has been very definitely recommended that no hospital should carry out the Wassermann reaction unless it has a well-trained laboratory staff headed by an experienced pathologist, and that even then results should not be relied upon unless the number of tests done each week is sufficient to ensure a continuity of technical practice (82, 83, 107). Furthermore, it has been felt that the Wassermann, good though it may be, is yet liable to error, especially in treated cases (45, 72). A search has therefore been instituted for tests that would be simpler, quicker, and, if possible, more sensitive than the Wassermann. As a result a number of flocculation tests have been devised, and these have been extensively tried by syphilologists and others (1, 5, 20, 23, 62, 88, 97, 99, 102, 114, 134). More recently, these flocculation tests have slowly found their way into mental hospitals, and whereas in the Board of Control Report for 1925 no mention is made of any of these tests, in 1930 no less than six of them were reported upon, one of them apparently having been used in five different hospitals (15, 16, 20, 21, 25, 30, 31, 34-36, 40, 42, 43, 48, 49, 100, 112, 113, 132, 133).