Abstract
I. On an occasion like this, when opportunity arises for students of immunity to meet for the discussion of their mutual problems, it seems fitting that, at least once during the meetings, the deliberations should take the form of a reëxamination of some of the fundamental premises on which our science is based. It is the business of most of us here to cast about continually for new leads, to leave the main highways of established fact and to follow more faintly marked paths to their endings. True progress can be made, and time and effort justified, only if we are sure, at each stage of our investigations that, so far, we have travelled straight. I assume that there are many of us here who have wasted effort on numerous occasions in trying to build at the top when the base needed support; and we all learn to recognize that endless repetition of experimental facts already well established, by slightly different methods and new manipulations, will bear dry fruit for science.
