M. XXXVIf. 3. DIGESTION, SECRETION, &c. 529 



that thofe were, when fir ft formed, appendages to 

 the nerves of fenfation or locomotion, or were form- 

 ed from them. And that hence all thefe folid parts 

 of the body, as they have originally confifted of 

 extremities of nerves, require an apportion of nu- 

 tritive particles of a fimilar kind, contrary to the 

 opinion of Buffon and Needham above recited. 



Laftly, as all thefe filaments have poffefTed, or 

 do poffefs, the power of contra&ion, and of confe- 

 quent inertion or elongation ; it feems probable, 

 that the nutritive particles are applied during their 

 times of elongation ; when their original conftitu- 

 ent particles are removed to a greater diftance from 

 each other. For each mufeular or fenfual fibre 

 may be coniidered as a row or firing of beads ; 

 which approach, when in contraction, and recede 

 during its reft or elongation ; and our daily expe- 

 rience fhews us, that great action emaciates the fyf- 

 tem, and that it is repaired during reft. 



Something like this is feen out of the body; for 

 if a hair, or a fingle untwifted fibre of flax or {ilk, 

 be foaked in water ; it becomes longer and thicker 

 by the water, which is abforbed into its pores. Now 

 if a hair could be fuppofed to be thus immerfed 

 in a folution of particles fimilar to thofe, which 

 compofe it ; one may imagine, that it might be 

 thus increafed in weight and magnitude ; as the par- 

 ticles of oak- bark increafe the fubftance of the hides 

 of beafts in the procefs of making leather. I men- 

 tion theft not as philofophic analogies, but as fi- 

 miles to facilitate our ideas, how an accretion of 

 parts may be effected by animal appetences, or fe- 

 ie&ions, in a manner fomewhat fimilar to mechani- 

 cal or chemical attractions. 



If thole new particles of matter, previoufly pre- 

 pared by digeflion and fanguification, only fupply 

 the places of thofe, which have been abraded by 

 the actions of die fyftem, it is properly termed nu- 

 trition. 



