IRRITABILITY, AND MUSCULAR POWER. 



103 



life to every other part, but that it is actually alive itself. " The difficulty," 

 says he, " of conceiving that the blood is endowed with life, while circu- 

 lating, arises merely from its being a fluid, and the mind not being accus- 

 tomed to the idea of a living fluid — I shall endeavour," he continues, 

 " to show that organization and life do not in the least depend upon each 

 other ; that organization may arise out of living parts and produce action, 

 but that life can never arise out of or produce organizition."* 



This is a bold speculation, and some part of it is advanced too hastily : 

 for instead of its being true, " that life can never arise out of or produce 

 organization," the most cursory glance into nature will be sufficient to con- 

 vince every man that organization is the ordinary, perhaps the only, mean 

 by which life is transmitted ; and that wherever life appears, its tendency, 

 if not its actual result, is nothing else than organization. But though he 

 failed in his reasoning, he completely succeeded in his facts, and abun- 

 dantly proved that the blood itself, though a fluid and in a state of circula- 

 tion, is actually endowed with Hfe ; for he proved, first, that it is capable of 

 being acted upon and contracting, like the solid muscular fibre, upon the 

 application of a stimulus ; of which every one has an instance in that cake 

 or coaguiuoi into which the blood contracts itself when drawn from the 

 arm^ probably in consequence of the srimuius oi the atmosphere. He 

 proved, ne^it, tn,ii lo al! degrees of atmospherical leir.i.e/sv'sjre whatever, 

 whether of heat or cold, which the body is capable of enduring, it pre- 

 serves an equality in its own temperature ; and in addition to this very 

 curious phaenomenon, he proved also, that a new-laid egg, the vessels of 

 which are merely in a nascent state, has a power of preserving its proper 

 temperature, and of resisting cold, heat, or putrefaction, for a considerable 

 period longer than an egg that has been frozen, or in any other way deprived 

 of its vital principle. Thirdly, he proved, in the instance of paralytic 

 limbs, that the blood is capable of preserving vitality when every other part 

 of an org^n has lost its vital power, and is the only cause of its not be- 

 coming corrupt. Fourthly, that though not vascular itself, it is capable, 

 by its own energy, of producing new vessels out of its own substance, and 

 vessels of every description, as lymphatics, arteries, veins, and even 

 nerves.! Finally, he proved, that the blood, when in a state of health, is 

 not only, like the muscular fibre, capable of contracting upon the appli- 

 cation of a certain degree of appropriate stmiulus, but that, like the mus- 

 cular fibre also, it is instantly exhausted of its vital power whenever such 

 stimulus is excessive ; and that the same stroke of lightning that destroys 

 the muscular fibre, and leaves it flaccid and uncontracted, destroys the 

 blood, and leaves it loose, and uncoagulated. 



Important, however, as these facts are, they do not reach home to the 

 question before us. They sufficiently establish the blood to be alive, but 

 they do not tell us what it is that makes it alive : on the contrary, they 

 rather drive us into a pursuit after some foreign and superadded principle ; 

 for that which is at one time alive, and at another thne dead, cannot be 

 life itself. 



The next theory, therefore, to which I have adverted, undertakes to 

 explain in what this foreign and superadded principle consists. Some ex- 

 quisitely SUBTLE GAS or AURA — somo fiuc, clastic, invisible fluid, sub- 

 limed by nature in the deepest and most unapproachable recesses of her 



* Hunter on the Blood, p. 20. 



t Dr. Munro has proved, that theUmb of a frog; can live and be nourished, and its wounds 

 heal, without any nerve. 



