160 ' LECTURE iV. 



ties of the leaves of plants, digests only 

 their juices, and voids the leaf dry, which 

 will afterwards unfold itself in warm water 

 as tea-leaves do. He knew that the fibrous 

 matter of vegetables, and the husks of 

 grain, are in general not susceptible of di- 

 gestion by the gastric fluids ; and yet that 

 some insects live upon them. Indeed they 

 first pour upon the woody substance a li- 

 quor which dissolves it, and in this state 

 they swallow and digest it. 



Thus also does that foe to literature, the 

 book-worm, make his way through the 

 most massy folios, solving the most diffi- 

 cult passages, and digesting all as he pro- 

 ceeds. Indeed he pours his sauce, or cook- 

 ing liquors with such profusion, as to tinge 

 and affect the texture of the leaves to some 

 distance round the circumference of the 

 tunnel which he makes. Some creatures 

 also thrive best upon animal substances in 

 a disgusting and noxious state of putre- 

 faction. Therefore it is evident, that life 

 can, by means of the fluids it prepares, con- 

 vert to its own purposes substances which 



