We have dedicated our work to the Commonwealth, but perhaps we should more specifically ascribe to the Massachusetts Commission on Mental Diseases (formerly the State Board of Insanity) the spirit that permitted our special study of neurosyphilis treatment. To these authorities, who have countenanced and encouraged a somewhat costly piece of special work since 1914, we offer our thanks, hoping that other states will be one by one stimulated to the state-endowment of research. States doing full duty by research can be counted on one hand. To our Psychopathic Hospital colleagues and the internes, and especially to Drs. Myrtelle M. Canavan and Douglas A. Thom of the Commission’s Pathological Service, we also offer our best thanks. The Danvers traditions are tangible here: cases of Drs. A. M. Barrett, H. A. Cotton, H. W. Mitchell, H. M. Swift, and others are presented. We have been especially aided by the more recent work of Dr. Lawson G. Lowrey. Nor should we have been able to present our samples of brain correlation without drawing on the collection arranged and analyzed by Dr. Annie E. Taft, Custodian, Harvard Department of Neuropathology. The photographs, part of a collection of brain photographs now numbering over 10,000 representing 700 brains of all sorts, were made by Mr. Herbert W. Taylor. The Wassermann testing work has been done by Dr. W. A. Hinton of the State Board of Health. Dr. Hinton himself wrote out the text description of the Wassermann method. The method of his laboratory is held to the standards of control set by previous chiefs, viz. by Professor F. P. Gay, who brought immunological methods direct from the laboratory of Bordet (whose method the Wassermann method essentially is), Prof. W. P. Lucas, and the late Dr. Emma W. D. Mooers, who had assisted Plaut in his first work with the Wassermann method in Kraepelin’s Munich Clinic. The material combed by us to secure this illustrative series amounts to over 2000 cases of syphilis of the nervous system, including over 100 autopsies in all types of case. We have presented these with very varying fulness, chiefly to illustrate the contentions at the heads of the case-descriptions. In using the book, we suggest early reference to the Summary and Key, where for convenience are placed numerous cross-references permitting extended illustration of almost every proposition from several cases. We have not made a large feature of the Medicolegal and Social section. This kind of thing well deserves a volume by itself, with all the legal and social-service implications drawn out in their amazing richness and detail. The social service slogan, “A paretic’s child is a syphilitic’s child” has already accomplished a great deal of good in our local world. Some day we may not be compelled to _drive_ the paretic’s spouse and offspring to the Wassermann serum test! The general practitioner must help here.