62 THE VITAL FUNCTIONS. 



hedge-hog rolls itself into a ball, presenting bristles 

 on every side; the diodon inflates its globular 

 body for the same purpose, and floats on the sea, 

 armed at all the points of its surface ; the cuttle- 

 fish screens itself from pursuit by effusing an in- 

 tensely dark coloured ink, which renders the 

 surrounding waters so black and turbid as to con- 

 ceal the animal, and favour its escape ; the torpedo 

 defends itself from molestation by reiterated dis- 

 charges from its electric battery ; the butterfly 

 avoids capture by its irregular movements in the 

 air, and the hare puts the hounds at fault by her 

 mazy doublings. Thus does the animated creation 

 present a busy scene of activity and employment : 

 thus are a variety of powers called forth, and an 

 infinite diversity of pleasures derived from their 

 exercise ; and existence is on the whole rendered 

 the source of incomparably higher degrees, as well 

 as of a larger amount of enjoyment than appears 

 to have been compatible with any other imaginable 

 system. 



>§ 2. Series of Vital Fwiclions. 



4 



In the animal economy, as in the vegetable, the 

 vital, or nutritive functions are divisible into seven 

 kinds, namely. Assimilation, Circulation, Respira- 

 tion, Secretion, Excretion, Absorption, and Nutri- 

 tion ; some of which admit of further subdivision. 

 This is the case more particularly with the pro- 

 cesses of assimilation, which are generally nume- 

 rous, and require a very complicated apparatus for 

 acting on the food in all the stages of its conversion 



