It is now well known that invasion of the central nervous system takes place early in the course of a syphilitic infection.1 In fact, it is the concensus of opinion that the fate of the nervous system in relation to this infection is usually determined during the first period of generalization of the disease.2 It has been asserted authoritatively that if the spinal fluid is negative at the time of the first examination, the test need not be repeated during the course of active treatment unless a lapse in treatment occurs.3 Such statements are qualified by the strict employment of modern principles of treatment in relation to the management of early syphilis. Rest intervals between courses of arsphenamin must be short, since the substitution of treatment at this early stage prevents the development of an immunity mechanism which would tend to hold the infection in check.4