In the course of an investigation detailed by one of us a year ago,1 it was found that when a normal guinea-pig was treated by a series of instillations of horse serum through the nose the results of the treatment, as tested by subsequent intravenous injections of horse serum, were always positive but in two opposite directions. In one group of animals the first intravenous injection of serum caused speedy "anaphylactic" death; that is, the individuals had been highly sensitized to horse serum by the instillations. In the other group of animals the first intravenous injection produced either no reaction or a variable degree of shock, and a second injection after an interval of three weeks was likewise withstood.
We have sought, in the present research, to determine the experimental conditions under which might be produced at will either increased specific sensitiveness or magnified resistance to
SEWALL H, POWELL C. STUDIES ON THE RELATIONS OF THE HYPERSUSCEPTIBILITY AND INSUSCEPTIBILITY INDUCED IN GUINEA-PIGS BY THE INSTILLATION OF HORSE SERUM INTO THE NOSE. Arch Intern Med (Chic). 1915;XVI(4):605-632. doi:10.1001/archinte.1915.00080040101007