ABSTRACT
This chapter shows several alkaloids and other substances are known to exert a powerful influence on the nervous system of animals. Hydrocyanic acid is so deadly a poison to animals, caused rapid movement of the tentacles. The chapter shows several substances affect the colour of the glands very differently. These often become dark at first and then very pale or white, as was conspicuously the case with glands subjected to the poison of the cobra and citrate of strychnine. Some essential oils, both in solution and in vapour, cause rapid inflection, others have no such power. Diluted alcohol is not poisonous, does not induce inflection, nor increase the sensitiveness of the glands to mechanical irritation. The vapour acts as a narcotic or anaesthetic, and long exposure to it kills the leaves. The vapours of chloroform, sulphuric and nitric ether, act in a singularly variable manner on different leaves and on the several tentacles of the same leaf.
