In the fishes, again, the distinction between the senses of smell and taste becomes more difficult, on account of their fluid environment. But, disregarding the distinction between smell and taste, the general chemical sense plays a very important part in the life of the fish. Now, some observers have included all of this sensitivity to chemical substances within the sense of smell, while others have attributed a part of it to a taste mechanism. As representative of the latter, Herrick’s conclusions are of interest: “In fishes the gustatory system is much more extensively developed than in mammals, especially the vagal part which supplies the taste buds in the gill region. In some species of fishes, moreover, taste buds appear in great numbers on the outer skin, and these are in all cases innervated from the seventh cranial nerve. In the common horned-pouts, or catfishes, and in the carps and suckers these cutaneous taste buds are distributed over practically the entire body surface, and especially on the barblets.... These sense organs and their nerves are entirely independent of those of the lateral line system, and of the ordinary tactual system, though the gustatory and tactual systems have been shown experimentally to coöperate in the selection of food.” Herrick determined by experiment that the sense organs thus generally distributed over the body of the catfish really had a taste function. Food placed at a distance from the fish produces only restless movements, indicating that the eyes do not direct them to it. But if food comes into contact with the mouth parts, or, in fact, any part of the body, it is immediately seized. To show that this reaction is not alone due to tactual stimulation, the tactual organs were first stimulated with cotton wool, which produced the characteristic seizing reaction. But after stimulation was continued for a while reaction no longer followed. If at this point the cotton wool be soaked with meat juice, the seizing reaction is again set up. Adaptation to tactual stimulation has taken place, leaving the taste organs to function alone. To show further that the responses did not depend on olfactory stimulation, the olfactory nerves of certain fishes were cut. When the experiment was performed, after recovery from the operation the responses were the same as in normal fish. The experiments of Parker show further that the mouth and external surface of the body of certain fishes are sensitive to sour, salt, and alkaline solutions. Sheldon obtained about the same results. The external skin covering is not sensitive to sugars. The tongue of fishes presents a smooth, gray, dorsal surface, devoid of elevations or papillæ, which characterize the tongues of many other organisms. Nor is it a mobile organ in comparison with other species. On the whole, the tongue itself seems little adapted for arousing taste sensations.