118 



ON THE BONES, &c. 



It is hence the cerambyx, and several other tribes of insects, are able to 

 make that shrill sound which they give forth on being- taken, and which ap- 

 pears like a cry from the mouth, but is in reality nothing more than the fric- 

 tion of the chest of the insect against the upper part of its abdomen and wing- 

 shells. And it is hence, also, that the ptinus Jatidicus, or death-watch, pro- 

 duces those measured strokes against the head or other part of a bed in the 

 middle of the night, which are so alarming to the fearful and superstitious ; 

 but which, in truth, are nothing more than a call or signal by which the one 

 sex is enticed to the other, and is merely produced by the insect's striking 

 the bony or horny front of its head against the bed-post, or some other hard 

 substance. 



Having, then, taken a brief survey of the elementary nature and chemi- 

 cal composition of these harder parts of the animal frame, I shall proceed to 

 make a few remarks upon the relative powers of each, and their diversified 

 applications amid the different kinds of animals in which they are em- 

 ployed. 



The BONES in their colour are usually white ; but this does not hold uni- 

 versally, for those of the gar-pike (esox belone) are green ; and in some varie- 

 ties of the common fowl they approach to a black : Abelfazel remarks this 

 of the fowls of Berar, and Niebuhr of those of Persepolis. 



The bones of an animal, wherever they exist, are unquestionably the 

 levers of its organs of motion : and so far the mechanical theorists are correct. 

 In man and quadrupeds, whose habits require solidity of strength rather than 

 flexibility of accommodation, they are hard, firm, and unpliant, and consist 

 of gluten fully saturated with phosphate and carbonate of lime. In serpents 

 and fishes, whose habits, on the contrary, demand flexibilit}^ of motion, they 

 are supple and cartilaginous ; the gluten is in excess, and the phosphate of 

 lime but small in proportion to it, and in some fishes altogether deficient in 

 the composition of their skeleton, though still traceable in their scales and 

 several other parts. In birds, whose natural habits demand levity, the bones 

 are skilfully hollowed out and communicate with the lungs, and instead of 

 being filled with marrow are filled with air, so that the purpose for which 

 the structure of birds was designed is as obvious, and as deeply marked, in 

 the bones as in the wings, whose quills also are for the same reason left hol- 

 low, or rather are filled with air, and in many tribes communicate with the 

 lungs as the bones do. 



The skeleton of the cuttle-fish (sepia officinalis) is extremely singular: its 

 back bone, for some purpose unknown to us, is much broader than that of any 

 other aquatic animal of the same size, and of course would be much heavier 

 but for a curious contrivance to prevent this effect, which consists in its 

 being exquisitely porous and cellular, and capable, like the bones of birds, of 

 becoming filled with air, or exhausted of it, at the option of the animal, in or- 

 der to ascend or descend with the greater facility. It is an animal of this 

 kind, or closely akin to it,* that inhabits the shell of the beautiful paper-nau- 

 tilus, and still more beautiful pearl-nautilus (argonauta and nautilus tribes), 

 and which hence obtain no inconsiderable portion of that lightness which en- 

 ables them, with their extended sails, to scud so dexterously before the wind. 

 In the calamary (sepia loligo) we meet with an approach towards the same 

 contrivance, in a kind of leafy plate introduced into the body of the animal ; 

 and even in the cloak of the slug-tribe we trace something of the same sort, 

 though proportionably smaller, and verging to the nature of horn. 



Generally speaking, the bones grow cartilaginous towards their extremi- 

 ties, and the muscles tendinous; by which means the fleshy and osseous 

 parts of the organs of motion become assimilated, and fitted for that insertion 



* The animal has commonly been supposed to be a real sepia or cuttle-fish ; but several naturalists have 

 of late doubted this, inasmuch as there are a few marks of distinction that seem to take it out of this genus. 

 Rafinesque has lience made another genus, for the purpose of receiving tliose which possess these dis- 

 tinctive signs ; and Dr. Leach has lately distinguished it specifically, in consequence of specimens senl 

 home from the unfortunate Congo expedition as collected by Cranch, by the name of Ocythoe Cranckii. 

 Even this animal, however, is regarded as a parasite in the shell, and only possessing it whfn empty. The 

 proper animal is not known to the present hour.— See Phil. Trans. 1817, p. 293 



