Tutin, the active principle of the toot-plant, causes epileptoid convulsions in various classes of animals. After large doses to rabbits the earliest convulsions commence with a general tonic spasm, which is followed by clonic movements. After small convulsant doses the convulsions begin with clonic spasms of the muscles of the head. These extend to the fore and then to the hind part of the body, and may terminate in a tonic spasm. The latter convulsions after larger doses also assume this form. After the initial convulsions following small doses, somersaulting movements are not uncommon.

The convulsions are mainly of cortical and pontine origin. Convulsive movements can be obtained when the brain is divided below the pons, but they are less characteristic and are more difficult to induce than when the pons is intact. In frogs the optic lobes seem to be the most important centres affected. Unequivocal conclusive movements were not obtained below a section of the spinal cord.

The convulsions arising in the pons are very susceptible to anaesthetics. This probably explains why convulsions are limited to one side after excision of one cerebral hemisphere during the continuance of the anaesthesia.

In unanaesthetized rabbits the two fore limbs act together, and the two hind limbs act in concert and synchronously during tutin convulsions; in the anaesthetized animal the limb-movements are often asynchronous. Individual muscles of the limbs often act vicariously, and this probably explains the irregular clonus which the movements of the limbs show.

Preceding the onset of the convulsions the medullary centres are stimulated. This effect is also produced by non-convulsant doses.

All doses which produce an obvious action cause in rabbits a fall of body temperature.

When heated with dilute caustic-alkali solutions, tutin rapidly decomposes, the product being pharmacologically inactive. Prolonged heating with dilute acids leads to the same result.

The substance most closely allied to tutin—namely, coriamyrtin—is a more powerful convulsant, and, for similar physiological doses, is more rapid and more transient in action than tutin.