The Reaction of the Rat to Diphtheria Toxin With Observations on the Technic of the Roemer Method of Testing Diphtheria Toxin and Antitoxin

Summary 1.Zingher9s method of injecting intracutaneously in guinea-pigs is described. 2.It is shown that constant results can be obtained with the Roemer technic only if the larger guinea-pigs are used (over 400 grams). 3.The rat is not absolutely immune to diphtheria toxin. Although it usually survives the injection of 1000 minimal lethal doses (for the guinea-pig) it regularly succumbs to 4000 such units. 4.The rat is capable of the production of antitoxin upon the repeated injection of diphtheria toxin. 5.The resistance of the rat to diphtheria toxin is not due to the presence of normal antitoxin, but to the property of the cells of preventing the toxin from entering them or of attaching itself to them.