ZOOPHYTES. 145 



strength. Some are qualified to dive into the 

 recesses of the deep ; others to flutter in the 

 light regions of air ; while, in many of the infe- 

 rior ranks, we find all these objects renounced 

 for the more certain advantage of security, 

 which the softer texture of the organs renders 

 one of paramount importance. That construc- 

 tion of limbs which favours certain movements 

 will necessarily interfere with the ready per- 

 formance of others, and must preclude the deve- 

 lopement of the organs which would be neces- 

 sary for facilitating them. Different kinds of 

 prey require dexterity in particular actions for 

 their pursuit and seizure. The animal is, in 

 one case, formed for climbing trees ; in another, 

 for burrowing in the earth : in a third, for perfo- 

 rating wood. Some are provided with organs 

 for penetrating into the bodies of other animals ; 

 others with the means of ensnaring their captives ; 

 while others, again, instil into the veins of their 

 victims a deadly poison. Hence it is necessary, 

 in studying the organization of animals, to 

 bestow particular attention on the habits and 

 mode of life for which each respective tribe and 

 species has been destined. 



In the examination of the mechanical func- 

 tions which will form the first part of this 

 treatise, I shall keep in view, as the leading 

 object of inquiry, the faculty of progressive 

 motion, noticing its different degrees of per- 



VOL. i. L 



