DEVELOPMENT OF VEGETABLES. 79 



analogy, as we shall afterwards have occasion to notice, to 

 that of the poisonous fangs of serpents. 



The purposes answered by the down, which covers a great 

 number of plants, are not very obvious. It perhaps serves 

 as a protection from the injurious effects of cold winds on 

 the tender surface: or it may have a relation to the deposi- 

 tion of moisture; or, as it may be farther conjectured, the 

 number of points which are thus presented to the air may be 

 designed to convey electricity from the atmosphere, or to 

 restore the electric equilibrium, which may have been dis- 

 turbed by the processes of vegetation. 



In the smaller parts of plants, as in the general fabric of 

 the whole, we find, on examination, the most admirable pro- 

 vision made, according to the particular circumstances of the 

 case, for the mechanical objects of cohesion, support, and de- 

 fence. Thus, the substance, of the leaf, of which the func- 

 tions require that a large surface be expanded to the air and 

 light, is spread out in a thin layer upon a frame-work of 

 fibres, like rays, connected by a net-work of smaller fibrils, 

 and constituting what is often called the skeleton of the leaf. 



In all these vegetable structures, while the objects appear 

 to be the same, the utmost variety is displayed in the means 

 for their accomplishment, in obedience, as it were, to the 

 law of diversity which, as has been already observed, seems 

 to be a leading principle in all the productions of nature. It 

 is more probable, however, judging from that portion of the 

 works of creation which we are competent to understand, 

 that a specific design has regulated each existing variation 

 of form, although that design may in general be utterly be- 

 yond the limited sphere of our intelligence. 



§ 4. Animal Organization. 



The structures adapted to the purposes of vegetable life, 

 which are limited to nutrition and reproduction, would be 

 quite insufficient for the exercise of the more active func- 

 tions and higher energies of animal existence. The power 

 of locomotion, with which animals are to be invested, must 

 alone introduce essential differences in their organization, and 



