Abstract

1. Injection of picrotoxin (1 µ g.) and aconitine (0.01 to 0.07 µ g.) into the infundibular region produce in rabbits a deep fall of temperature accompanied by cardiac symptoms due to a central vagal stimulation.

2. The cooling effect of picrotoxin is suppressed by luminal and paraldehyde, but picrotoxin annuls simultaneously the fall of temperature produced by these drugs. In other kinds of experimental temperature fall (calcium sleep, aconitine) picrotoxin shows an additative or even potentiated cooling effect.

3. The evidence so far collected in the experiments speaks in favour of the existence of temperature lowering (cooling) centres and supports the view of the dual structure of the temperature regulating centres.