OF DEATH, OR CESSATION OF NUTRITION. 613 



those functional operations, in which vital activity consists, upon the due 

 supply of the circulating fluid. And as a general rule we find, that the more 

 active the changes which normally take place in any tissue during life, the 

 more speedily is its complete loss of activity, or Death, when the requisite 

 conditions of its vital action are no longer supplied to it. We may observe 

 that, in Cold-blooded animals, the supervention of Molecular upon Somatic 

 death is much less speedy than it is in Birds and Mammals. This seems 

 clue to two causes. In the first place, the tissues of the former, being at all 

 times possessed of a lower degree of vital activity than those of the latter, 

 are disposed to retain it for a longer time; according to the principle already 

 laid down. And, secondly, as the maintenance of a high temperature is an 

 essential condition of the vital activity of the tissues of warm-blooded ani- 

 mals, the rapid cooling of the body after Somatic death is calculated to extin- 

 guish it speedily; and that this cause has a real operation, is evinced by the 

 influence of artificial warmth in sustaining the vital properties of separated 

 parts. The rapidity with which Molecular death follows the cessation of the 

 general circulation, will be influenced by a variety of causes ; but especially 

 by the degree in which the condition of the solids and fluids of the body has 

 been impaired by the mode of death. Thus in Necraemia, and in death by 

 gradual cooling, Molecular and Somatic death may be said to be simultane- 

 ous; and the same appears to be true of death by sudden and violent impres- 

 sions on the Nervous System. But in many cases of death by causes, which 

 suddenly operate in producing Syncope or Asphyxia, the tissues and blood 

 having been previously in a healthy condition, Molecular death may be long 

 postponed. We cannot be quite certain that it has supervened, until signs of 

 actual decomposition present themselves. 



816. When Molecular death takes place in an isolated part, it must result 

 from some condition peculiar to that part, and not primarily affecting the 

 body in general. Thus we may have Gangrene or Mortification of a limb as 

 a direct result of the application of severe cold, or of an agent capable of 

 producing chemical changes in its substance, or of violent contusions occa- 

 sioning mechanical injury; or, again, from an interruption to the current of 

 nutritive fluid; or, further, from some ill-understood stagnation of the nutri- 

 tive process, which manifests itself in the spontaneous death of the tissues 

 without any assignable cause, as in some cases of Senile Gangrene. Some- 

 times we are enabled to trace this stagnation to some disordered condition of 

 the circulating fluid; as in the Gangrene resulting from the continued use of 

 the Ergot of Rye or Wheat; but we can give no other account of the almost 

 invariable commencement of such gangrene in the extremities, than we can 

 of the selection of Lead, introduced into the blood, by the extensors of the 

 fore-arm. When Mortification or Molecular Death is once established in any 

 part, it tends to spread, both to contiguous and to distant portions of the body. 

 Thus we have continually to witness the extension of Gangrene of the 

 lower extremities, resulting from severe injury or from the use of the Ergot, 

 from the small part first affected, until the whole limb is involved; and this 

 extension is easily accounted for by our knowledge of the tendency of organic 

 substances in the act of decomposition, to produce a similar change in other 

 organic substances subjected to their influence. And the propagation of the 

 Gangrenous tendency to other parts, is obviously due to the perversion of the 

 qualities of the Blood, which results from a similar cause. It is not, how- 

 ever, until some organ is affected, whose action is essential to the due main- 

 tenance of the Vegetative functions, that Molecular death becomes a cause of 

 Somatic death ; and very extensive ravages may thus take place without the 

 extinction of the sufferer's life. 

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