820 TOUCAN TOUCH behind. They are peculiar to tropical Amer- ica, living in flocks in the forest, where they make a great chattering as they hop from branch to branch in search of food ; they feed principally on pulpy fruits, also on fish, eggs, larvro, and small birds and reptiles ; they also saw off the tubular corolla of flowers, pick- ing out the insects with the horny, fimbriated tongue. When roosting they throw their tail upward and forward, and rest the enormous bill on the back. They are generally hand- some birds, representing in America the horn- bills of Asia and Africa ; they are not power- ful fliers, and are strictly arboreal, hopping among the branches with such grace and agil- ity as to have suggested for one of them the specific name of Ariel. The nest is in holes in trees, and the eggs are two, rounded and white. They post a sentinel while they feed, whose warning cry resembles the word tucano ; the skin is bluish, and the flesh eatable though rather tough ; they sometimes commit great havoc with fruit, and are often killed for food and for their brilliant feathers ; they are very sensitive to cold. In the toucans proper (ram- phastos, Linn.) the bill is higher and wider than the forehead, looking as if too large for the head and belonging to another bird; the nostrils are hidden behind the prominent base ; wings short and rounded, with the first four quills graduated and narrowed at the tip, and the fifth the longest; tail short and nearly even ; feet short and stout ; colors generally black with patches of white,' red, and yellow, especially under the chin. The toco toucan (R. toco, Gmel.) is 17 in. long, and the bill is more than half of that length ; plumage black with throat and rump white, vent red, bill orange red with black tip ; it inhabits Guiana and Brazil. The yellow-breasted toucan (R. tucanus, Linn.) has a yellow throat, with red Yellow Toucan (Pteroglossus Humboldtti). vent and breast spot, and the rest of the plu- mage black. There are more than a dozen oth- er species. In the genus pteroglossus (Illig.), generally called aracaris, the bill is much small- er and sometimes not out of proportion to tLe head, as high as the forehead, with the nos- trils conspicuous at the base ; fourth, fifth, and sixth quills longest; tail long and graduated; the colors are usually green, with red or yellow on the breast. There are more than 30 spe- cies, with habits similar to those of the last genus. The aracari toucan (P. aracari, Illig.) is 17 in. long, with a bill of 4 in. ; plumage blackish green, with yellowish abdomen, red median abdominal bar and rump ; upper man- dible with a longitudinal black stripe. The yellow toucan (P. Humboldtii, Gould) is 17 in. long, black and olive with a scarlet rump, and the under surface yellow ; it is found on the upper Amazon. For description and figures of this family, see Gould's " Monograph of the RamphastidaB " (fol., London, 1834). TOUCH, the modification of the common sensibility of the body, especially seated in the skin, by which through physical contact we obtain an idea of resistance or weight, tem- perature, size, shape, smoothness or roughness, &c. It is most acute at the tips of the fingers, on the tongue, lips, portions of the mucons membrane, and the nipples, where the sensory papilla are the most numerous, each one re- ceiving one or more nerve fibres. The nerve fibres appear to terminate in what has been called the tactile corpuscle in the interior of the papilla. All the afferent nerves of the general integument apparently minister to the sense of touch, by virtue of their connection with the seat of common sensation in the brain ; those of the lower extremities are less con- cerned in conveying sensations than those of the upper, though they are far more efficient in exciting the reflex action of the spinal cord. The acuteness of touch differs in various parts of the body, generally in proportion to their vascularity; the non-vascular parts, like the hair, nails, and teeth, have no sense of touch, while on the skin the nerves are spread in a minute network. Its relative acuteness has been measured by Weber, by placing the legs of a pair of compasses on the skin, and approxi- mating them until brought within the smallest distance at which they could be felt as distinct points, and with the following results: the point of the tongue, line ; palmar surface of third finger, 1 lino ; red surface of lips, 2 lines; tip of nose, 3 lines ; edge of dorsum of tongue, 4 lines ; skin of cheek, palm of hand, and end of great toe, 5 lines; back of hand, 8 to 14 lines; back of foot, 18 lines; over spine, and in middle of arm and thigh, 30 lines. There are considerable variations in this respect in different individuals. The feeling of tickling is most easily excited in parts having a feeble sense of touch, as the arm pits, sides below the ribs, palms, and soles, while the sensitive points of the fingers cannot thus be affected. This sense is exceedingly acute in the flying mem- brane of the bats and in the whiskers of the carnivora and rodents. It is combined with movement in the human hand, with its power
