NATURAL THEOLOGY. 183 



ing fluid resists putrefaction most pertinaciously ; 

 nay, not only checks its further progress, but re- 

 stores putrid substances. 



4. It is not ?i fermentative process ; for the solu- 

 tion begins at the surface, and proceeds towards 

 the centre, contrary to the order in which fermen- 

 tation acts and spreads. 



5. It is not the digestion of heat ; for the cold 

 maw of a cod or sturgeon will dissolve the shells 

 of crabs or lobsters, harder than the sides of the 

 stomach which contains them. 



In a word, animal digestion carries about it the 

 marks of being a power and a process completely 

 sui generis, distinct from every other, at least from 

 every chemical process with which we are ac- 

 quainted. And the most wonderful thing about it 

 is its appropriation — its subserviency to the par- 

 ticular economy of each animal. The gastric juice 

 of an owl, falcon, or kite will not touch grain ; no, 

 not even to finish the macerated and half-digested 

 pulse which is left in the crops of the sparrows 

 that the bird devours. In poultry, the trituration of 

 the gizzard, and the gastric juice, conspire in the 

 work of digestion. The gastric juice will not dis- 

 solve the grain whilst it is whole. Entire grains 

 of barley, enclosed in tubes or spherules, are not 

 affected by it. But if the same grain be by any 

 means broken or ground, the gastric juice imme- 

 diately lays hold of it. Here then is wanted, and 

 here we find, a combination of mechanism and 



