Physiological Disturbances during Experimental

Rabbits weighing approximately two kilograms were used as the experimental animals. They were maintained on a fasting regime, which began 24 hours before the injection of the toxin and continued thereafter. Water was always present in the cages. Three groups were studied. The first group of 5 animals served as fasting controls. Each of the second group (6 animals) received intravenously 3 minimal lethal doses of diphtheria toxin. The third group (8 animals) each received 0.8 intravenously. (Previous work had demonstrated that these quantities of toxin would cause death in from 2 to 3 days and 4 to 7 days, respectively.) The blood electrolyte studies were made 1 or 2 days before the expected death of the animals. Because of the relatively large amount of blood needed (20 to 25 cc.), cardiac punctures were employed. The blood was collected under oil, allowed to clot, centrifuged, and the serum removed as soon as possible. Before withdrawal of the blood, the animal was anesthetized by the intraperitoneal injection of 0.5 cc. of 10 per cent sodium amytal solution per kilogram of body weight. This procedure was used in order to eliminate the effects of struggling. The hemoglobin determinations were made before the injection of the toxin, and every day thereafter. The blood was obtained from a freely flowing wound made by a small incision through a marginal ear vein. The methods employed for the chemical determinations were the following: bicarbonate, manometric method of Van Slyke and Neill using 0.2 cc. (2); chloride, Patterson micromodification of the open Carius method (3); phosphate, Benedict and Theis (4); total base, Stadie and Ross modification of the Fiske method (5) without removal of phosphate; sodium, Barber and Kolthoff method (6); potassium, Shohl and Bennett method (7); nitrogen, Kjeldahl method, using 1 cc. (the factor 6.25 was used to obtain per cent protein); non-