Horse serum, kept for 2 hours at 38°C. in the presence of one-fifth its volume of a suspension of 0.5 per cent of pararabin inphysiological salt solution and then freed by means of centrifugalization and filtration from the pararabin produced when injected in appropriate doses into a normal rabbit, a considerable and prolonged fall of the blood pressure, a distinct retardation in the coagulation of the carotid blood, and sometimes, in addition, acceleration of the respiratory rate and the expulsion of numerous scybala; that is, the various symptoms observed to occur after the intravenous injection of horse serum in sero-anaphylactized rabbits. If the horse serum is first heated for 30 minutes to 56°C. and then treated with pararabin in the manner described above, the intravenous injection of this serum into a normal rabbit exerts no more action on the arterial pressure, the coagulability of the arterial blood, the respiratory rate, and the intestinal activity, than does normal horse serum when introduced into the vein of a normal rabbit.
On page 227, Vol. XXV, No. 2, February 1, 1917, line 20, for 2 or 3 minutes read 20 to 30 minutes. On page 228, lines 28, 29, and 30 should read: It should also be mentioned, as has been shown by the experiments of Bordet and Zunz with guinea pigs, that it is better to employ homologous serum; that is, rabbit serum.
The intravenous injection of horse serum, kept for 2 hours at 38°C. in the presence of one-fifth of its volume of a suspension of 0.5 per cent agar in physiological salt solution and then separated from the agar by centrifugalization and filtration, produces in normal rabbits in adequate doses a considerable and prolonged fall in the blood pressure, expulsion of feces, a diminished coagulability in the carotid blood, and at times accelerated respiration; that is, the various symptoms observed after the intravenous injection of horse serum in a seroanaphylactized rabbit. Horse serum previously kept for 30 minutes at 56°C. and then treated with agar in the manner described above, when injected intravenously into a normal rabbit will have no more effect on the arterial pressure, on the intestinal movement, on the respiratory rate, or the coagulation of arterial blood than the introduction of horse serum into the veins of a normal rabbit.