Sect. XXXVII. 3. 1. SECRETION, &c. 363 



inflamed •, it follows, that thofe were, when firH: formed, ap- 

 pendages to the nerves of fenfation or locomotion, or were 

 formed from them. And that hence all thefe folid parts of the 

 body, as they have originally confided of extremities of nerves, 

 require an appofition of nutritive particles of a fimilar kind, 

 .contrary to the opinion of Buffon and Needham above recited. 



'JUaftly, as all thefe filaments have pofTerTed, or do pofiefs, the 

 power of contraction, and of consequent inenion or elongation ; 

 it feems probable, that the nutritive particles are applied during 

 their times of elongation \ v/hen their original conflituent par- 

 ticles are removed to a greater diftance from each other. For 

 each mufcular or fenfual fibre may be confidered as a row or 

 firing of beads ; which approach, when m contraction, and re- 

 cede during its reft or elongation j and our daily experience 

 ihews us, that great action emaciates the fyftem, and that it is 

 repaired during reft. 



Something like this is feen out of the body 3 for if a hair, or 

 a fingle untwifted fibre of flax or filk, be foaked in water j it be- 

 comes 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 particles of oak-bark increafe the fubftance 

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

 tion thefe not as philofophic analogies, but as fimilies to facili- 

 tate our ideas, how an accretion of parts may be effected by 

 animal appetences, or felections, in a manner fomewhat fimilar 

 to mechanical or chemical attractions. 



If thofe new particles of matter, previoufly prepared by di- 

 geftion and fanguification, only fupply the places of thofe, which 

 have been abraded by the actions of the fyftem, it is properly- 

 termed nutrition. If they are applied to the extremities of the 

 nervous fibrils, or in fuch quantity as to increafe the length or 

 craffitude of them, the body becomes at the fame time enlarged, 

 and its growth is increafed, as well as its deficiencies repaired. 



In this laft cafe fomething more than a fimple appofition or 

 felection of particles feems to be neceffary ; as many parts of 

 the fyftem during its growth are caufed to recede from thofe, 

 with which they were before in contact ; as the ends of the 

 bones, or cartilages, recede from each other, as their growth 

 advances : this procefs refembies inflammation, as appears in 

 ophthalmy, or in the production of new flefn in ulcers, where 

 old vefTels are enlarged, and new ones produced j and like that 

 is attended with fenfation. In this fituation the vefTels become 

 iteftended with blood, and acquire greater fenfibility, and may 



th u$ 



