118 ON THE BONES, &c. 



renew them in full perfection in about twelve weeks. These antlers are real 

 bones ; and those of the elk are sometimes as heavy as half a hundred pounds 

 weight, and in a fossil state in Ireland have been dug up still heavier, and 

 of the enormous measure of eight feet long, and fourteen feet from tip to tip , 

 on beholding which, we may well, indeed, exclaim with Waller, 



O fertile head ! which every year 

 Could such a crop of wonders bear. 



Tn like manner, many species of the crab and lobster tribes annually throw 

 off and renew the whole of their crustaceous covering, and apparently with- 

 out any very great degree of trouble. The animal at this time retires 

 to some lonely and sheltered place, where, in its naked and defenceless state, 

 it may avoid the attack of others of the same tribe which are not in the- same 

 situation : a line instinctively drawn now separates the shell into two parts, 

 which are easily shaken off, when the secernent vessels of the skin pour forth 

 a copious efflux or sweat of calcareous matter all over the body, the more 

 liquid parts of which are as rapidly drunk up by the absorbent vessels, so 

 that a new calcareous membrane is very soon produced, which as speedily 

 hardens into a new calcareous crust, and the entire process is completed in 

 about a fortnight. This genus, also, in many of its species, is capable of re- 

 producing an entire limb, with the whole of its calcareous casing, whenever 

 deprived of it by accident or disease, or it voluntarily throws it off, as I have 

 already observed it is capable of doing, to extricate itself from being seized 

 hold of; though the new limb is seldom so large or powerful as the original. 

 So, in other animals, we sometimes find a large and preternatural secretion of 

 calcareous matter, in consequence of a diseased habit of particular organs, or 

 of the system generally. The human kidneys are too often subject to a mor- 

 bid affection of this kind, whence a frequent necessity for one of the most 

 painful operations in surgery. The chalkstones, as they are erroneously 

 called, that are often produced in protracted fits of gout and rheumatism, 

 are rather lithate of soda than any compound of lime ; but instances are not 

 wanting in which one of the lungs has been found converted into an entire 

 quarry of limestone. 



In the Transactions of the Royal Society there are several cases related 

 of young persons who, in consequence of a morbid habit, threw out a variety 

 of calcareous excrescences, either over the hands and feet, or over the whole 

 body ;* and about four years since, a Leicestershire heifer was exhibited for 

 a show in this metropolis, the head and neck of which were completely im- 

 bedded in horny excrescences of this kind, and the back and limbs profusely 

 sprinkled over with them : some of the horns, and especially those about the 

 dew-lap, were as long and as large as the natural horns of the forehead, but 

 they were much more calcareous and brittle. A calcareous scurf, moreover, 

 was secreted over every part of the skin, which, whenever the skin was 

 scratched or bitten, united with the fluid that oozed forth, ramified, and diva- 

 ricated into masses of small roses. At the request of the (proprietor I took 

 an account of this extraordinary animal, and have since communicated it to 

 the Royal Society. In all other respects it was in good health ; its size was 

 proportionate to lit age, and its appetite enabled it to digest foods of every kind 

 equally; and though, in consequence of this, its diet had been frequently 

 varied, the propensity to a secretion of calcareous matter continued the same 

 under every change. 



It appears, therefore, very doubtful whether the animal economy be not at 

 times capable of generating lime, as well as gelatin or albumen, out of the 

 different materials introduced into the stomach in the form of food. Vauquelin 

 endeavoured to decide the question by a variety of experiments upon the 

 nature of the egg-shells of a sitting hen, and an examination into the propor- 

 tion of calcareous matter contained in a given weight of shells, compared 

 with the calcareous matter furnished by her food, and that discharged as a 



* See also Mr. Baker's account of the porcupine-man, Phil. Trans, for 1755 



