Blalock “demonstrated that surgical shock is not due to the elaboration of toxins nor to reflex neurologic mechanisms, but … to decrease in circulating the blood volume” (M.M. Ravitch). He wrote many papers on the subject, principally experimental studies; Ravitch considered this paper from 1930 the most important (see Johns Hopk. med. J., 1977, 140, 57-67, for bibliography).