Of the properties of organic life, the sensible contractility is wanting in the glandular system. But the two other properties are developed in it to the highest degree. They are in constant activity; secretion, excretion and nutrition keep them in incessant action there. It is by its organic sensibility that the gland distinguishes, in the mass of blood, the materials which are proper for its secretion. It is by its insensible contractility, or its tonic forces, that it contracts to throw out those which are foreign to this secretion. The first is on a small scale in each gland, what the animal sensibility of the tongue and the nostrils is on a large one, which allows only aliments suitable for the stomach to be introduced into its cavity; the other does insensibly, what is effected in so evident a manner by the glottis, when it rises up convulsively against a foreign body that attempts to enter it. The blood contains the materials of all the secretions, of the nutrition of all the organs, and of all the exhalations. Each gland draws from this common reservoir what is necessary to its secretion, as each organ does what is proper for its nutrition, and as each serous surface does what is suitable for its exhalation. Now it is by its organic sensibility that each living part of the body distinguishes what its functions require. When the fluids enter the small vessels of the gland, this sensibility is the sentinel that gives notice of it, and the insensible contractility is the agent which opens or closes the gates of the organ, according to the principles that are presented. This comparison, if I may be allowed the use of it, gives an idea of what then takes place. Every glandular action turns then especially upon these two properties, and as this action is almost permanent, they are then constantly in exercise.