208 



of a thermometer. All is reduced to a simple counter- 

 poise. 



23. The nourish nj eut of the more perfect animals re- 

 quires to be more wrought than that of plants. Hence 

 the necessity of the circulation of the Hood. The prepara- 

 tions of the sap do not require such a punctual, regular, 

 and constant motion ; bare poisings suffice. Large ani- 

 mals eat but at particular times: a pressing sensation 

 which induces them to take nourishment, does not con- 

 tinually act upon them. The different preparations 

 their aliment should undergo, would be disturbed or in- 

 terrupted, were a fresh supply to be received within 

 them before the former was sufficiently digested, 



Plants, on the contrary, are in a slate of perpetual 

 suction ; they draw in nourishment continually, and in 

 a very great quantity, in the day-time by their roots, in 

 the night by their leaves. There is a plant which re- 

 ceives and transpires, in the space of twenty-four hours, 

 twenty times more than a man. 



But if plants differ so much fi\**n large animals by 

 circulation, on the other hand same species of animals 

 seem nearly to resemble plants by their want of this cir- 

 culation. Not the least appearance of this motion is to 

 be perceived in the polypus, the tape-worm, ihr pond- 

 muscle, and divers other shell-fish. 



24. One of the ancients defined a plant to be a roofed 

 animal. He would undoubtedly have defined an ani- 

 mal to have been a wandering plant. The loco-motive 

 faculty is one of those characters which present, them- 

 selves first, when we compare the vegetable Kingdom 

 with the animal. We see plants that, are constantly 

 fixed on the earth. Being incapable of seeking their 

 nourishment, it is ordained that this nourishment shall 

 seek them. The, greatest part of animals on the con- 

 trary, are subjected to the care of providing their own 

 subsistence. Nature has not always deposited Lear 

 them such nourishment as was necessary for their sup* 



