The diagnosis of early congenital syphilis as a rule is not difficult. The diagnosis of the same disease in later childhood is often a matter of great difficulty. Careful inquiry into the history, both family and personal, may throw no light on the case, and the characteristic signs which would enable one to make a diagnosis may be slight, or entirely absent; yet, later, perhaps at the age of puberty, such signs do arise and the diagnosis is evident. Undoubtedly such cases are syphilitic from the onset, but run a "latent" course, perhaps for several years, and then under certain conditions break out in a more pronounced form.
The diagnosis being thus at times difficult, any measures leading to ease and certainty of detection are eagerly welcomed. Studies of recent years have given us three such measures: the detection of the Spirochœta pallida in the secretions or tissues of the