IG THE PHILOSOPHT 



ted purpofes of fecretion and nutrition. The ftructure of 

 plants is more iimple j they receive perpetual nourifhment 

 without injury. Animals fearch for and feledl particular 

 kinds of food. But plants mufb receive whatever is brought 

 to them by the different elements. Animals exift on the 

 furface and in the interior parts of the earth. In the air, in 

 water, in the bodies of men and other animals, in the internal 

 parts of plants, and even in ftones. But if we except a £q\y 

 aquatics, plants are fixed to the earth by roots. 



All animals, it has been affirmed, have a heart, or particu- 

 lar fountain for propelling and diftributing their fluids to 

 the different parts of their bodies : but caterpillars, and ma- 

 ny other infects, have no fuch general receptacle. 



The loco-motive faculty has been confidered as peculiar to 

 animals. But even this character is extremely fufplcious, 

 Oyfters, fea-.nettles, the gall-infects, and a variety of » other 

 animals, can hardly be faid to enjoy the povv^er of local mo- 

 tion. Many fpecies remain forever fixed to the rocks on 

 which they are produced, and have no motion but that of 

 extending or contraiSling their bodies. Beiides, examples 

 of different kinds of motion are difcoverable irf the vegetable 

 kingdom. When the roots of a tree meet with a ffone, or 

 any other obftrudlion to their motion, in order to avoid it, 

 they change their former dire<Elion. They turn from barren 

 to fertile earth, which indicates fomething analogous to a fe?- 

 lection of food. Like the polypus, plants, when confined In 

 d houfe, uniformly bend toward the window or aperture 

 through which the rays of light are introduced. 



The fenfitive plant poffeffes the faculty of motion in* an 

 eminent degree. The fllghtefl touch makes its leaves fud- 

 denly fhrink, and, together with the branch, bend down 

 toward the earth. But the moving plant, or hedyfarum 

 movens, of which there are fpecimens in the botanic garden 

 of Edinburgh, furniflies the moft aftonifliing example of ver 



