Some of these, such as resins, gums, essential oils and fats, are readily obtained as natural exudations or by very simple manipulations, while others, such as the alkaloids, glucosides and vegetable acids, often require to be extracted by very complex processes.
Amongst the latter, the vegetable poisons of known constitution, alkaloids, glucosides, &c., are to be placed.
Some appear to be glucosides of gallic acid, since they yield this acid and a sugar on hydrolysis, e.g.
Digitalis contains four important glucosides, of which three are cardiac stimulants.
Gay-Lussac. It is present in varying amounts in certain plants, being a product of the hydrolysis of the cyanogenetic glucosides, e.g.