322 ON ZOOLOGY. 



mitted, we might have descended to the com- 

 parative digestive organs of the amphibia; of 

 fishes; and of the still lower order of animals, 

 insects and ivoims; in which, though upon simpler 

 principles, the same beautiful contrivance, and 

 the same varied adaptation of the means to the 

 end, have been displayed. But I trust I have 

 sufficiently treated on the subject to convince 

 you through what diversified resources Provi- 

 dence has effected her object; and while the dif- 

 ferent purposes of the animal have been answer- 

 ed, each living substance has been endued with 

 the most ample means of enjoyment and preser- 

 vation, consistently with the ends for which it 

 has been created. 



Having conducted the prepared fluid previous- 

 ly submitted to three distinct operations into the 

 blood vessels, we are next led to inquire what 

 further process is requisite to qualify it to answer 

 the double purpose of nutriment to the body at 

 large, and of affording those various secretions 

 necessary to preserve in due tone its several parts. 



In my former paper, when treating on vegeta- 

 bles, we noticed that the sap did not acquire a 

 nutritive principle, until it had been deprived of 

 its grosser materials by evaporation, and had taken 

 up new ingredients from the atmosphere; and that 

 this was effected by tubes, which conveying the fluid 

 from the roots to the leaves, it was there by a very 



