3 6o DIGESTION, SECT. XXXVII. i. i. 



SECT. XXXVIL 



OF DIGESTION, SECRETION, NUTRITION. 



I. Cryjlals tncreafe by the greater attraclion of their Jides. Accre- 

 tion by chemical precipitations, by welding^ by preflure, by aggluti- 

 nation. II Hunger ', digejlion^ why it cannot be imitated out of 

 the body. Lacleals abforb by animal feleclion^ or appetency. III. 

 The glands and pores abforb nutritious particles by animal felecHon. 

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

 elongation of fibres. Like inflammation. IV. It feems eafier to 

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

 from inirrit ability* Three cau/es of this. Original fibres of the 

 organs of fenfe 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 refiftance is nothing, it is certain the fides of thefe cubes 

 would attract each other ftronger than their angles ; and hence 

 that thefe eight fmaller cubes would fo arrange themfelves as to 

 produce one larger one. 



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

 pofitions of diflblved calcareous or filiceous particles, as are feen 

 in the formation of the ftalaCtites of limeftone in Derbyfhire, or 

 of calcedorie in Cornwall Other means of adhefion are produ- 

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

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

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

 nation of a third fubftance penetrating the pores of the other 

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

 Though the 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 j yet it does not appear, that 

 their original organization was produced by chemical laws, and 

 their production and increafe muft therefore only be looked for 

 from the laws of animation. 



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

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

 palates, excite into aUon 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 



