32 THE PHILOSOPHY 



This fimilarity in the general ftru(9:ure of animals and 

 plants is ftrongly corroborated by the analogous parts in both 

 being deftined to anfwer the fame purpofes. 



The oeconomy and functions of vegetables, as well as thofe 

 of animals, are the refults of a vafcular texture. Each of 

 thefe claiTes of beings have veiTels deftined to the perform- 

 ance of fimilar offices. In man and quadrupeds, the fluids 

 are circulated by the pulfation of the heart and arteries. 

 The juices of plants do not circulate j but they are raifed 

 from the root to the trunk, branches, leaves, flowers, and 

 fruit by the fap-velTels. The afcenfion of the fap has been 

 afcribed to capillary attraflion. But, though no motion is 

 perceptible in the fap-velTels Iimilar to the puliation of arte- 

 ries ; yet, both the propullion of the fap, which moves w^itli 

 great force, and the fecretion of different fluids by different 

 parts of the fame plant, imply an a61:ion in thefe veffels. In 

 animals, the gall, the urine, the faliva, are all concocted from 

 the general mafs of blood by the adtion of particular veffels. 

 Fluids of thefe different qualities exift not in the blood itfelf ; 

 they are created by an incomprehenflble operation of the 

 veffels peculiar to their refpe6live glands. In plants, the fap 

 afcends, and different fluids are fecreted from it by glandular 

 veffels. Here the fame effects are produced both in the an- 

 imal and the plant. We muff, therefore, attribute them to 

 the fame caufe, namely, the adion of veffels. Befides, the 

 fap, which is the blood of plants, moves with a force often 

 equivalent to the weight of the atn)ofphere. M. Bonnet 

 remarks*, that he has feen, by means of coloured liquors, 

 the vegetable fap move three inches in an hour j and Dr. 

 Hales, in his ftatics, has fhown, that the leaves are the prin- 

 cipal organs of tranfpiration. He like wife confiders them 

 to be the infrruments which raife the fap. But it has fince 

 been difcovered, that coloured liquors rife equally high in 

 * Oeuvres, torn. i.p. 140. 



