COMPARATIVE ANATOMY. 



a sixth sense to these animals. It is pro- 

 bably analogous to that of touch. The 

 nerves of the wing are large and nume- 

 rous, and distributed in a minute plexus 

 between the integuments. The impulse 

 of the air against this part may possibly be 

 so modified by the objects near which the 

 animal passes, as to indicate their situa- 

 tion and nature. 



In geese and ducks the bill is covered 

 with a very sensible skin, supplied with 

 an abundance of nerves from all the three 

 branches of the fifth pair. This appara- 

 tus enables them to feel about for their 

 food in mud, where they can neither see 

 nor smell it. None of the amphibia or 

 fishes seem to possess the sense of touch, 

 according to the acceptation stated a- 

 bove. 



All the observations and investigations 

 of the structure of the antennae, those 

 peculiar organs which exist universally 

 in the more perfect insects, and of the 

 use vvhich these animals generally apply 

 them to, lead us inevitably to the con- 

 clusion, that they really are proper or- 

 gans of touch, by which the animal ex- 

 amines and explores surrounding ob- 

 jects. Such organs are particular!) 7 ne- 

 cessary to insects, on account of the in- 

 sensibility of their external coat, which is 

 generally of a horny consistence, and also 

 from their eyes being destitute in most in- 

 stances of the power of motion. 



Most of the herbivorous mammalia, par- 

 ticularly among the bisulca, have their 

 tongue covered with a firm and thick cuti- 

 cular coat, which forms numberless point- 

 ed papillae, directed backwards. These 

 must assist, according to their consistence 

 and direction, at least in the animals of 

 this country, in tearing up the grass. 

 Animals of the cat kind have their tongue 

 covered with sharp and strong prickles, 

 which must enable the animal to take a 

 firm hold. Similar pointed processes are 

 found in some other animals ; as in the 

 bat kind, and the opossum. 



There seems to be no doubt, that in all 

 the mammalia which we have now con- 

 sidered, the tongue is an organ of taste, 

 at least towards its anterior part. 

 ' The toothless animals, on the contrary, 

 as the ant-eater and manis, which swallow 

 their aliment whole, have a worm-like 

 tongue, which is obviously capable of no 

 other use than that of taking their food. 



The tongue of the wooclpecker has a 

 very singular structure, which admits of 



its being darted out of the mouth for 

 some inches : It is used for the purpose 

 of catching insects, and is horny and 

 barbed at its extremity. In the frog and 

 chameleon, the tongue is also the organ 

 by which the prey is seized. In the for- 

 mer animal it is long, soft, and covered 

 with a glutinous slime. In the quiescent 

 state it lies from before backwards in the 

 mouth, from which it is darted at the 

 prey, consisting of insects, which become 

 entangled by the viscid fluid. The tongue 

 of the chameleon displays a very curious 

 mechanism. It is contained in a sheath 

 at the lower part of the mouth ; and has 

 its extremity covered with a glutinous se- 

 cretion. It admits of being projected to 

 the length of six inches, and is used in 

 this manner by the animal in catching its 

 food, which consists of flies, &c. It is 

 darted from the mouth with wonderful 

 celerity and precision, and the viscous se- 

 cretion on its extremity entangles the 

 small animals which constitute the food 

 of the chameleon. 



ORGAN OF SMELLIJfG. 



Two remarkable instances of anomalous 

 structure in parts connected with the nose 

 occur in the proboscis of the elephant, 

 and the blowing holes of the cetacea- 

 The former organ consists of two canals, 

 separated from each other by an inter- 

 vening partition. Innumerable muscular 

 fasciculi, running in two directions, occu- 

 py the space between these and the in- 

 teguments. There are fibres of a trans- 

 verse course, passing like radii from the 

 canals to the integuments, and others, 

 which run in a more longitudinal direc- 

 tion, but -have their extremities turned 

 inwards. The former extend the trunk, 

 without causing any contraction of the 

 canals ; the latter bend or contract it ; 

 and both tend to bestow on it that won- 

 derful mobility which it possesses, in eve- 

 ry direction. 



The more longitudinal fibres are divid- 

 ed at short intervals by tendinous inter- 

 sections, which enable the animal to bend 

 any part of the organ, and to give it any 

 requisite degree of curvature. The same 

 structure will confer a power of bending 

 different parts of the trunk in opposite di- 

 rections; indeed, there is no kind of cur- 

 vature which may not be produced by 

 these longitudinal fibres. These fascicu- 

 li occupy the external surface of the or- 

 gan. The transverse fibres are not all 

 arranged like radii round the canals ; but 

 some pass across from right to left, and 



