Cinchona alkaloids - quinine, quinidine, cinchonine, and cinchonidine have a remarkable power of arresting these movements in the proportion of 1 in 1,500. They quickly stop the migratory movements of leucocytes from the newt, and in a much larger proportion will arrest the movements of the knoblike pseudopods.

No very marked difference is observed in the strength of the cinchona alkaloids, though quinine seems to be somewhat the most powerful.

Sulphate of bebeerine is almost as powerful as the cinchona alkaloids.

Strychnine is very much less powerful than any of the alkaloids mentioned.

Potassium picrate and aesculin have but little action.3

1 Kuhne, Protoplasma und Contractilitat, pp. 28-53.

2 Geltowsky, Practitioner, vol. viii. pp. 325-330.

3 Buchanan Baxter, Practitioner, vol. xi. p. 321.