Site of Action of D.D.T. and Cause of Death after Acute D.D.T. Poisoning

Abstract

EXPERIMENTS were carried out with Periplaneta americana and Rana esculenta, after injection with a D.D.T.-emulsion. Action-potentials from the n. cruralis (= 5th nerve, Pringle) of the second thoracic ganglion of Periplaneta were recorded with a special pre-amplifier and a cathode-ray oscillograph. No differences were found between normal and D.D.T.-treated animals in the following preparations : (1) crural nerve only connected with the second leg ; (2) crural nerve only connected with the second thoracic ganglion, which was isolated from the other ganglia and from all peripheral nerves. Hence the D.D.T. causes no increase of spontaneous activity of the sense organs of the leg, nor of spontaneous motor-activity from the isolated ganglion. However, when the reflex path was intact (or partly intact—crural nerve connected with second leg and second thoracic ganglion), the action-potentials of D.D.T.-treated animals showed an abnormal increase in frequency.