QIQ TRAINING OF AKIMALS, &C. 



tion; of the debility produced by the moft natural powers 

 fupporting life, namely, the wafte of fubftance created by 

 that exercife and labour, for which we feem peculiarly def- 

 tined," — all thefe expreffions are extremely fufpicious. The 

 fpeciilator is always to be fufpedted, when, forfaking plain di- 

 redl fads, he involves his want of meaning, and confcious ig- 

 norance, in learned words, or metaphor. 

 It is ufually fup. Thefe metaphorical expreffions have originated in a per- 

 an/other foliT ' ^"afion, that the bones, cartilages, mufcles, and other folid 

 parts are perma- parts, being once formed, are permanent, becaufe the identity 

 are" fucceffiveiy °^ *'^^ individual is permanent ; and that being once formed, 

 replaced, like and always retaining one (liape, their a6iual component parts 

 the fluids. jj^^j^ continue the fame. Nothing in philolbphy is farther 



from the truth. There are experiments to demonftrate, that 

 every part and particle of the firmed bones, is fucceflively 

 abforbed and depofited again *. The folids of the body, 

 whatever their form or texture, are incefiantly renewed. The 

 whole body is a perpetual fecretion, and the bones and their 

 ligaments, the mufcles and their tendons, all the finer and all 

 the more flexible parts of the body, are as continually renewed, 

 and as properly a fecretion, as the faliva that flows from the 

 mouth, or the moifture that bedews the furface. The health 

 of all the parts, and their foundnefs of ftrudure, depends on 

 this perpetual abforption, and perpetual renovation ; and ex- 

 ercife, by promoting at once abforption and fecretion, pro- 

 motes life, without hurrying it; renovates all the parts and 

 organs, and preferves tliem apt and fit for every office. 

 "Nutrition is a Nutrition belongs not to the flomach alone, which but pre- 

 general procefs. pg^es the food, and converts it into chyle, but to the velTels 

 by which it is circulated, and appropriated to the nutrition of 

 parts, which of courfe is performed by every petty artery of 

 the body. 

 Many general In nothing fiiould we be more anxioufly careful, than, in 

 laying down rules, which muft afTecl the health of ihoufands ; 

 and whenever we proceed on do6lrines, unfupported by fa£l, 



* This has been afcertained by giving madder to growing animals, 

 efpecially pigs and fowls, among their food. It is found that the 

 madder tinges the bones, layer after layer, with a red colour; and 

 by the Jecpnefs of the tinge, demonftrates the fuccelfion in which 

 the particles of the bone are abforbed and depofited. This is, I 

 believe, the concliifion which pbyfiologifts have formed. 



wherever 



lules are rafli 

 and d.mgerous< 



