ox VEGETATION. 79,5 



electricity; the stamina of the barberry and of the pellitory are thrown into 

 motion, when touched with a needle, and those of rue, and of the grass of 

 parnassus, have at times alternate motions without any apparent cause. A 

 zoophyte is an animal absolutely fixed to one place; and the vallisneria is a 

 vegetable possessed of a certain limited power of locomotion. A plant 

 chooses in preference to turn towards the light; and it has been known that 

 an ash tree on a wall, when incapable of being any longer supported by the 

 wall only, has concentrated all its force in tbe production of one large root, 

 descending to the ground. Some of these circumstances may be explained 

 without recurring to any thing like volition; but, as far as wc know, the 

 same explanations might be applied to some animal motions: and although it 

 is very possible that there may be a certain limit, where the influence of mind 

 and sensation terminates, and the laws of vegetable life only prevail; yet the 

 place of the division is not strongly enough marked, to allow it to form a 

 characteristic in an artificial system. It has, been asserted that some worms 

 are nourished by absorption only, without the assistance of a stomach; thus 

 hydatids, which are supposed to be of an animal nature, appear to be simply 

 bags of a fluid without any visible opening; but a few doubtful cases of this 

 kind can scarcely be sufficient, to invalidate the general position, that all bodies 

 decidedly animal have a cavity for the reception of food. There are usually 

 also some chemical distinctions in the component parts of animals and vege- 

 tables; animal substances commonly containing greater proportions of azote 

 or nitrogen, and of phosphoric acid; but there are some exceptions to this ob- 

 servation; thus the carica papaya, or papaw, contains nearly the same prin- 

 ciples as are usually found in substances of animal origin. In general we may, 

 readily distinguish a small portion of an animal from a vegetable substance, 

 by the smell produced in burning it. According to common language, W£ 

 say, that minerals have growth only, but not always; that vegetables grow 

 and live also; and that animals have sensation, as well as life and increase of 

 magnitude. 



Mineralogy is a branch of natural history so nearly allied to chemistry, 

 that it cannot be completely understood without a previous knowledge of that 

 science. It may therefore be more properly considered as belonging to a 

 course of chemical than of physical lectures. 



VOL. I. 4 X 



