ZOOPHYTES. Ill 



ter in its immediate vicinity. It is exposed so the action 

 of the surrounding elements, and affected by their vicissi- 

 tudes, without the means of retreat, and without the power 

 of reaction. With respect to all external agents, indeed, ve- 

 getables may be regarded as passive beings. Very different 

 are the condition and destination of animals. Excepting 

 a few among the lower orders of the creation, such as Zoo- 

 phytes and MoUusca, all animals are gifted with the power 

 of spontaneously changing their situation, according to their 

 several wants and necessities, and are thus enabled to seek 

 and to choose those objects which are salutary, and to avoid 

 or reject those which are injurious. Nature has, for these 

 purposes, furnished them with a more complex organization 

 and more varied powers, adapted to a greater diversity of 

 pursuits, and to a higher and more expanded sphere of ex- 

 istence. 



The power of progressive motion is enjoyed in very dif- 

 ferent degrees by different races of animals, according to the 

 particular model on which they are constructed, and the re- 

 lations which their organization bears to the element assigned 

 as their residence. All the mechanical circumstances in 

 their economy, indeed, are so closely linked together, as 

 scarcely to admit of being considered separately. Thus, we 

 find, in one animal, a variety of mechanical effects accom- 

 plished by one and the same instrument; while, in others, 

 they are each produced by a separate and distinct organ. In 

 some, the leading principle of the construction is simplicity; 

 in others, the most elaborate mechanism is displayed. But 

 the means have constant reference to the design, and are ever 

 varied in exact conformity with the change of purpose. The 

 relative advantages of each plan of structure appear to have 

 been carefully estimated, and studiously balanced. Each 

 quality has been bestowed in different degrees of perfec- 

 tion; so that in following the series of gradation among the 

 successive tribes of animals, we occasionally meet with fa- 

 voured species, endowed with great superiority in some 

 particular faculty. Some animals excel in swiftness; others 

 in strength. Some are qualified to dive into the recesses of 

 the deep; others to flutter in the light regions of air; while, 



