#• DIGESTION, Sect. XXXVII. 2. 4 





SECT. XXXVII. 



OF DIGESTION, SECRETION, NUTRITION. 



I. Cry ft a! s increafe by the greater attraction of their fides. Accre- 

 tion by chemical precipitations , by welding, by prejjure, by aggluti- 

 nation. II. Hunger, digeftion, why it cannot be imitated out of 

 the body. Lacleals abforb by animal [election , or appetency. III. 

 The glands and pores abforb nutritious particles by animal feleclion. 

 Organic particles of Buff on. Nutrition applied at the time of 

 elongation of fibres. Like inflammation. IV. It feems e after to 

 have preferved animals than to reproduce them. Old age and death 

 from inirr it ability. Three caufes of this. Original fibres of the 

 organs cffenfe and mufcles unchanged. V. Art of producing 

 long life. 



I. The larger cryftals of faline bodies may be conceived to 

 arife from the combination of fmaller cryftals of the fame form, 

 owing to the greater attractions of their fides than of their an- 

 gles. Thus if eight cubes were floating in a fluid, whofe fric- 

 tion or refinance is nothing, it is certain the fides of thefe cubes 

 would attract each other ftronger than their angles 5 and hence 

 that thefe eight fmaller cubes would to arrange themfelves as to 

 produce one larger one. 



There are other means of chemical accretion, fuch as the de- 

 pofitiens of diifolved calcareous or filiceous particles, as are fec*n 

 in the formation of the fbakuftites of limeftone in Derby (hire, or 

 of calcedone in Cornwall. Other means of adhefion are produ- 

 ced by heat and prefiure, as in the welding of iron-bars ; and 

 other means by fimple preflure, as in forcing two pieces of ca- 

 outchou, or elaftic gum, to adhere ; and laftly, by the aggluti- 

 nation of a third fub fiance penetrating the pores of the other 

 two, as in the agglutination of wood by means of animal gluten. 

 Though die ultimate particles of animal bodies are held togeth- 

 er during life, as well as after death, by their fpecific attraction 

 of cohefion, like all other matter ; yet it does not appear, that 

 their original organization was produced by chemical laws, and 

 their production and increafe mult therefore only be looked for' 

 from the laws of animation. 



II. When the pain of hunger requires relief, certain parts of 

 the material world, which furround us, when applied to our 

 palates, excite into action the mufcles of deglutition ; and the 

 material is fwallowed into the ftomach. Here the new aliment 

 becomes mixed with certain animal fluids, and undergoes a 



chemical- 



