406 On ike Phi/siology of Fege talks. 



object of my study, and enables me to investigate more deeply/. 

 It ceitainiv, however, makes my progress slower: — but 1 have 

 l>een rather accused of doing loo much, than too Ullle; though 

 I do not know how that can be the case, unless 1 have done 

 taielesslv and ill what I perform or discover. 



Perhaps the next thing necessarv to the obtaining a thornngh 

 knowledge of the formation of plants, and to comprehend their 

 real physical nahiie, is to estal)lish as exact an idea of the situa- 

 tion t'.iey hold in the animal and in the iiiunimule ivorld as 

 possible. I have already done this in some measure ; but I still 

 think a mucii more discriminating ])ictnre may be presented, — 

 that by drawing the limits that in vegetables cannot be passed, 

 and by fixing the boundaiy lines of such a being as a vegetable 

 really is, will at once conect all rhose false ideas we are per- 

 petually introducing, though so foreign to its very vattire. 



For example : As a plant has no brain, no nerves, or spine, no 

 heart, it can have no voluntary motion ; it ran be moved by its 

 muscles only, that is, h\ i\vAtvis insiln it most truly possesses: it 

 can therefore have no sensation, no feeling, for sensation and vo- 

 luntarv motion coincide ; nor, when compared with inanimate 

 matter, can it be niox'ed, as that is, bv the introduction of ca- 

 loric, by some mechanical agent separating its parts, or some 

 chemical agent altering its c(mit)inations. 



If therefore a motion is perceived in a vegetable, it connot be 

 attributed to its air or its juices, to w hich it is I'Ut loo cummorily 

 rejerri'd, without considering that such motion belongs not to 

 its nature: but the cause must be sought in that which is ana- 

 losous to il^form, which agrees with and appertains to its life. 

 — Nor can the jui..es of the vegetable be said to circvlalp, since 

 that is against the laws estal)lished for that species of being ; 

 no animal or beiiig having a circulation that is not possessed of a 

 sint<h heart, through which the whole mass of blood can pass, 

 and in which it may be said to centre. Nor can the juices of any 

 animal or being be said to circulate, where its juices are taken 

 in or respired ihrougliout the whole of their surface. Plant.^ 

 respire by means of their hairs; — many insects by nearly the 

 same cause. " No animal," says Cuvier, " respires by a par^ 

 iicular organ, except those which have a real circu!ati(m; be- 

 cause in them the blood coming from one common source, the 

 heart, to which it returns, the vessels that contain it are so dis- 

 posed, it cannot arrive at the other parts till it has passed 

 through the lungs." This of course cannot take place in vege- 

 tables, that have no heart ; nor is there any place in plants at 

 all analogous to that part. I have before given innumerable 

 other reasons why this circulation (on which Mr. Knight so in- 

 bists) is impossible; and the late discoveries make it still more 



so. 



