An increasing widespread use is apparent of tests for syphilis said to be so sensitive that a negative result "excludes" syphilitic infection1 while a positive result is "presumptive" evidence of syphilis.2 Confirmation by a less sensitive and more specific procedure is, of course, necessary before such tests can be considered of diagnostic significance. Several aspects of these tests should give pause to serologists and physicians alike, for they promise to cause serious errors, both of omission and of commission, in the diagnosis and treatment of syphilis.
The first criticism concerns nomenclature. Not merely does no laboratory test yet devised "exclude" syphilis, but no laboratory test even excludes the presence of serum reagin.3 Moreover, it is not necessarily true that a serum giving a negative Kline exclusion or Kahn presumptive result will be negative by every other technic used. In any extended series of tests, certain syphilitic serums