Abstract

1. Quebrachine is by far the most toxic of the four alkaloids investigated.

2. In small doses quebrachine exerts a stimulating action on the central nervous system, as also do the other alkaloids. The only obvious objective effect of this is seen in the respiration, which becomes both quicker and deeper.

3. The chief action of quebrachine in larger doses is a paralysing effect on nerve-cells; this includes nerve-cells on the autonomic system, the brain and cord.

4. After first paralysing nerve-cells quebrachine in still larger doses paralyses the vagus, the sympathetic and motor nerve-endings.

5. Quebrachine belongs to the curare-nicotine-coniine group of drugs. It causes death by paralysing the respiratory centre at a time when the motor nerves are still responsive to electrical stimulation.