120 ON THE BONES, &c. 



of South America, found among trees, and a devourer of other insects 

 and even small birds. It is of so enormous a size that its fangs are equal 

 to the talons of a hawk ; and its eyes, which are eight in number, arranged 

 as a smaller square in the middle of a larger, are capable of being set in the 

 manner of lenses, and used as microscopes. 



In many animals, especially the herbivorous, the tongue itself is armed 

 with a serrated apparatus, the papillae being pointed and recurvated, and ena- 

 bling them to tear up the grass with much greater facility. In the cat-kind 

 the tongue is covered with sharp and strong prickles, which enable the ani- 

 mal to take a stronghold; and similar processes are met with in the bat and 

 the opossum. In the lamprey and myxine families, the tongue itself is co- 

 vered with teeth. In that grotesque and monstrous bird the toucan, whose 

 bill is nearly as large as its whole body, the tongue is lined with a bundle of 

 feathers, of the use of which, however, we are totally ignorant, though it is 

 probably an organ of taste. 



In the crab and lobster tribes the teeth are placed in the stomach, the whole 

 of which is a very singular organ. It is formed on a bony apparatus, and 

 hence does not collapse when empty. The teeth are inserted into it round 

 its lower aperture or pylorus : their surface is extremely hard, and their mar- 

 gin serrated or denticulated, so that nothing can pass through the opening 

 without being perfectly comminuted. The bones and teeth are moved by 

 peculiar muscles. It is a curious fact, that at the time the animal throws off 

 its shell, it also disgorges its bony stomach and secretes a new one. 



The teeth of the cuttle-fish are arranged not very differently, being situated 

 in the centre of the lower part of the body ; they are two in number, and horny, 

 and in their figure exactly resemble the bill of a parrot. 



The teeth of the echinus genus (sea-hedgehog) are of a very singular arrange- 

 ment. A round opening is left in the centre Of the shell for the entrance of 

 the food : a bony structure, in which five teeth are inserted, fills up this aper- 

 ture ; and as these parts are moveable by numerous muscles, they form a very 

 complete organ of mastication. 



Such is the variety which the hand of nature, sometimes, perhaps, sportive, 

 but always skilful, has introduced into the structure and arrangement of the 

 teeth of animals, or the organs that are meant to supply their place. 



The SKIN AND ITS APPENDAGES offer an equal diversity, and constitute the 

 next subject of our inquiry. 



All living bodies, whether animal or vegetable, are furnished with this inte- 

 gument : in all of them it is intended as a defence against the injuries to 

 which, by their situation, they are commonly exposed ; and in most of them 

 it also answers the purpose of an emunctory organ, and throws off from the 

 body a variety of fluids, which either serve by their odour to distinguish the 

 individual, or are a recrement eliminated from its living materials. 



This integument accompanies animals and vegetables from their first forma- 

 tion : it involves equally the seed and the egg ; and possessing a nature 

 less corruptible than the parts it encloses, often preserves them uninjured for 

 many years, till they can meet with the proper soil or season for their healthy 

 and perfect evolution. 



This is a curious subject, and must not be too hastily passed over. After 

 fish-ponds have been frozen to the very bottom, and all the fishes contained 

 in them destroyed ; or after they have been completely emptied, and cleared 

 of their mud ; eels and other fishes have been again found in them, thougn no 

 attempt has been made to restock the ponds. Whence has proceeded this 

 reproduction 1 Many of the ancient schools of philosophy, and even some 

 of those of more modern date, refer us to the doctrine of spontaneous gene- 

 ration, and believe that they have here a clear proof of its truth. But this is 

 to account for a difficulty "by involving ourselves in one of a much greater 

 magnitude. It is a petitio principii which we stand in no need of, and which 

 we should be careful how we concede. The reproduced fishes have alone 

 arisen from the ova of those which formerly inhabited the fish-pond ; and 

 which, from some cause or other, had sunk so deep into the soil, as to be 



