104 ON THE PRINCIPLE OF LIFE, 



nary section of the Levitical code ; a doctrine, indeed, of no new invention, 

 even at that early period, but probably derived expressly from' the ritual of 

 the higher patriarchs, if we may be allowed to appeal to a similar belief and 

 a similar practice among the Parsees, Hindoos, and other oriental nations of 

 very remote antiquity, who seem rather to have drawn this part of their cere- 

 monial directly from the law or tradition of the patriarchs, than indirectly 

 from that of the Jews. 



Among- the Greeks and Romans, were the authority of the poets to be of 

 any avail, we should imagine that this hypothesis never ceased to be in repu- 

 tation : for the nop(pvp£og OdvaTog, ov purple death, of Homer, and the purpurea 

 animaj or purple life, of Virgil (phrases evidently derived from this theory), 

 are commonplace terms amid all of them: but the real fact is, that among 

 the philosophers, we do not know of more than two, Empedocles and Critias, 

 who may be fairly said to have embraced it. 



In modern times, however, this hypothesis has again dawned forth, and risen 

 even to meridian splendour, under auspices that entitle it to our most attentive 

 consideration. Harvey, to whom we are indebted for a full knowledge of the 

 circulation of the blood, may be regarded as the phosphor of its uprising ; 

 Hoffman speedily became a convert to the revived doctrine ; Huxham not 

 only adopted it, but pursued it with so much ardour, as, in his own belief, to 

 trace the immediate part of the blood in which the principle of life is dis- 

 tinctly seated, and which he supposed to be its red particles. But it is to that 

 accurate and truly original physiologist, Mr. John Hunter, that we can only 

 look for a fair restoration of this system to the favour of the present day, or 

 for its erection upon any thing like a rational basis. By a variety of import- 

 ant experiments, this indefatigable and accurate observer succeeded in proving 

 incontrovertibly that the blood contributes in a far greater degree, not only to 

 the vital action, but to the vital material of the system, than any other con- 

 stituent part of it, whether fluid or solid. But he went beyond this discovery, 

 and afforded equal proof, not only that the blood is a means of life to every 

 other part, but that it is actually alive itself. " The difficuHy," says he, "of 

 conceiving that the blood is endowed with life, while circulating, arises 

 merely from its being a fluid, and the mind not being accustomed to the idea 

 of a living fluid. — I shall endeavour," he continues, " to show that organiza- 

 tion 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 organization."* 



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 organ- 

 ization," the most cursory glance into nature will be sufficient to convince 

 every man that organization is the ordinary, perhaps the only, means 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 abundantly proved that 

 the blood itself, though a fluid and in a state of circulation, is actually endowed 

 with life : for he proved, first, that it is capable of being acted upon and con- 

 tracting, like the solid muscular fibre, upon the application of a stimulus ; of 

 which every one has an instance in that cake or coa^ulum into which the 

 blood contracts itself when drawn from the arm, probably in consequence 

 of the stimulus of the atmosphere. He proved, next, that in all degrees of 

 atmospherical temperature whatever, whether of heat or cold, which the body 

 is capable of enduring, it preserves an equality in its own temperature; and 

 in addition to this very curious phenomenon, he proved also, that a new-laid 

 egg, the vessels of which are merely in a nascent state, has a power of pre- 

 serving 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 



» Hunter on the Blood, p. 20 



