Hence, from this point of view, the difference between animals and plants consists in this; that, in the latter, the contractile substance, as a primordial utricle, is enclosed within an inert cellulose membrane, which permits it only to exhibit an internal motion, expressed by the phenomena of rotation and circulation, while, in the former, it is not so enclosed.

The protoplasm in the form of the primordial utricle is, as it were, the animal element in the plant, but which is imprisoned, and only becomes free in the animal; or, to strip off the metaphor which obscures simple thought, the energy of organic vitality which is manifested in movement is especially exhibited by a nitrogenous contractile substance, which in plants is limited and fettered by an inert membrane, in animals not so.

compartment; cell, cellule; follicle; hole, corner, niche, recess, nook; crypt, stall, pigeonhole, cove, oriel; cave &c (concavity) 252. capsule, vesicle, cyst, pod, calyx, cancelli, utricle, bladder; pericarp, udder.