2456. The tongue is a feeling-sense in water, just as the skin was that in the air. For it is the blossom of the digestive process. To the tongue therefore belongs the digestive or water-organ of the mouth, which is constituted by the salivary glands.
2457. The sensation of what is fluid in its chemical relations is called taste. Gustation is not a peculiar process, but obviously only the nervous commencement of the digestive process. On that account also the gustatory sense still lies concealed in a cavity. The whole buccal or oral cavity still belongs to the sense of taste.
2458. As in the sense of feeling the motor system still predominates, so does it also in the tongue, as being the second sense, which has been liberated from the plant. The nervous mass is in this sense not preponderant over the muscular and bony mass.
2459. The tongue is still to be regarded as an organ of touch, though one in which the flesh or muscle has gained a mastery over the bones, while in the true tactile organ the bones determine the principal forms and functions. The tongue is a nervous organ in the muscle, the hand is such in the bone.
2460. The hyoid or lingual bone is none other than the first branchial arch, and consists pretty nearly of the same pieces as the arm.
2461. Compound lingual bones, such as occur in many Reptiles, have originated from coalescence of several branchial arches.
2462. Like the limbs, so is the tongue originally a double organ. In most Reptiles it is longitudinally fissured. Such animals have usually also a double penis. In all animals the tongue is divided into two moieties, which are only connate by means of suture. The penis also consists of two connate penes.
2463. As in the tegumentary sense, the nerves could not be peculiar or special in kind, but took their origin from all parts, and particularly from the spinal cord, so also is this the case with the intestinal sense, which is still only an internal tegumentary sense. The lingual nerves proceed from several situations, and that too from the upper part of the spinal cord.
2464. The oral cavity also consists, properly speaking, of mere tactile organs, which have been repeated in the head. Thus, there are tactile organs which are subservient to the gustatory sense, in biting, chewing, and swallowing.
2465. The lips are tactile organs upon the threshold or brink, as it were, of the gustatory sense.