Letter from Michael Heidelberger to Enrique E. Ecker, Western Reserve University

In this letter, Heidelberger rearticulated criticism of laboratory findings and methods reported by Ecker and his coworkers, criticism first advanced in the manuscript of a forthcoming article by Heidelberger and others on the comparison between human and guinea pig complement. The letter illustrates Heidelberger's role as arbitrator, critic, and guardian of a uniform terminology in the new field of complement chemistry, a field Heidelberger helped launch in the late 1930s and early 1940s. He proved that complement was made up of a group of specific chemical substances that could be isolated in the laboratory, and that it had essential functions in activating host defense mechanisms against invading microorganisms.