85 Comparative Anatomy ', or an Attempt at 



the cause of all voliinfarj/ motion to the muscles. Cuvier thinks 

 that they are the ciuise of all motion, both voluntary and in- 

 voluntary; but tiiat certainly cuiinct le, since the muscles of a 

 plant hnve the same vis iv^iia, without possessing avy nerves. 

 But there may undoubtedly be a sort of vapour, which may pass 

 through the nerves from the brain, and cause a most powerful 

 effect, but still be entirely separate from that visinsita which is 

 so peculiar to the musries, that no one who has seen it act both 

 in the human bodij and vegetatdes can confound it with any 

 other sort oi motion. The human muscle is a bundle of vessels: 

 the oil lubricates them, that they may not be hurt by (constant 

 friction: and this is exactly the case also with tiie vegetable ; but 

 the cases of both muscles are even more wonderful than the hair- 

 like fibril they eacli contain . The huu>an case appears to be formed 

 of twosorts of vessels; the fibril already described (which also enters 

 into the forniation of the case, and runs longifvdliially in it), 

 and another sort of vessel which forms a line and space, and 

 passes across the muscle, and gives such a beautiful shining lucid 

 appearance to the mi/sclc case, and by its hclj) draws up both 

 vessels. The crossing vessels are alternately filled wilh a white 

 oily matter, and the spaces between (being perfectly empty) by 

 the help of the nerve which gatiiers up longitudinally, the cross 

 vessels are drawn into rihs one above and one below, which run- 

 ning in a forked manner produce tiiat lucid ajipearance admired 

 by surgeons. When a piece of the muscle case is drawn out, 

 and left to dry, it becomes clear and horny : and if when in this 

 state it is lient to and frc very often, the place swells up, and 

 appears of a hlueish milky colour, which I supposed to be caused 

 bv the oil given cut from the cross vesseh. The nerves also 

 (which pass throx;gh the muscles) are with this management 

 Iroken and dispersed out of their cases ; and it is then they are 

 seen running in an undulating manner through the oily com- 

 pound, wh^ch, now the vessels are destroyed, retain only a matter 

 much resembling the in;j)Prvious skin of tl;e vegetable, only a 

 more oily composition. The vegetable muscle-case, like the 

 human, has also the fibril muscle in it: it is formed of straight 

 vessels, replete with oil ; but often so brittle they will not bear 

 to be bent. These vessels are at some distance from each other, 

 and laced up by the spiral wire. Though the figure of each 

 case does not possess a very strong resemblance, yet their effects 

 are the same : they have both the moveable fibrils within, the 

 oil to lubricate, the case to protect the white oily vessels also ; 

 no point is war. ting to prove that they are intended to produce 

 the same effect, though perhaps set in motion by ii different 

 cause. There can be no doubt that light and moisture are^ the 

 hidden causes of the vegetable motion, since their direct obe^ 



dience 



