a Comparison letween Animal a?id Vegetalle Life. S3 



other part of the lody, Jilted to convey her commands and in- 

 fluence over the whole. For botli these purposes, 7ierves are 

 (idaptcd ; tliev convey all tlie sensations to the mind, and give 

 notice of all suifering. It is evident, therefore, that all sensations 

 arise from tlie impression of some active substance on some 

 nerve of the hiitnan body ; and that the same is represented to 

 the mind by tlie means of the nerves connected with the brain : 

 every nerve, therefore, that is irritated produces a sense of pain; 

 and if certain parts of the brain are compressed, from which 

 particular nerves arise, then those senses are lost which depend 

 on those nerves. But in the iiijuries of the spinal medulla 

 (which is a continuation of the brain down the vertebrce of the 

 back) this is still more evident; for those parts wiiich receive 

 their nerves arising from the place injured in the medulla, are 

 either convulsed if that be irritated, or rendered paralytic if 

 that be compressed (and if the greater part of the brain siifferSy 

 the whole lody loses its power of motion) . These things con- 

 sidered, there seems to be no doubt that the cause of all sensibi- 

 lity arises from the nerves being connected with the brain or 

 spinal medulla ; and that all voluntary motion equally arises 

 from the connexion of the nerves with the muscles, thus convey- 

 ing its orders to aiid from the brain. Therefore it cannot re- 

 side in the nerves themselves ; because otherwise the moving 

 cause would continue to act after being separated from the brdin, 

 nor would it be increased by its irritation. 



Of all this important and admirable formation of the human 

 body, what part does the vegetable possess ? Scarcely anv that 

 can deserve to be assimilated to so wonderful and marvellous a 

 stnicture of senses and feelings ; though it has certainly great 

 beauty, not only from its simplicity, but arising also from the fit- 

 ness of its form, so admiraljly adapted to its situation in the 

 grand scale of beings; but without volition, without sensibilitij, 

 even without senses. The line of life can only be said to be the 

 hrain, spinal medulla, and heart to the phait, to stand for all 

 three, though it resembles the heart only as the first visible life, 

 and the brain alone as the chief source of existence, and the 

 spinal medulla as passing like the line of life through the i)ody. 

 But how inferior an image of all! It has not the action of the 

 heart, having neither arteries nor blood to circulate ; nor the brain, 

 having no nerves- I have entered more minutely into this than 

 I intended, in order to impress on my readers a conviction I feel 

 myself, that, thus formed, there can be no volilio?i in plants. 



To begin then with the description of the line of life (the only 



part that can be compared to the brain and spine of an animal). 



The line is formed of a matter firmer than the bark, not so hard 



a« tl^e wood, generally of a white colour, but sometimes green, 



F 2 sometin\ed 



