350 OF NUTRITION. 



series of years. The digestive, assimilating, and excreting organs, as 

 they were the first to coine to maturity, are commonly the first to fail 

 in their activity ; but this is very generally the result of over-exertion 

 of their powers, the amount of food introduced into the stomach being 

 rarely (among the higher and middle cjasses of society at least) kept 

 down to the real wants of the system. The muscular apparatus usually 

 experiences the effects of this diminished nutrition, sooner than the 

 nervous system ; the vigour of the latter being often sustained in a 

 remarkable degree (as shown by the energy of the mental operations) 

 through a protracted life, when it has not been overtasked at an earlier 

 period. The very slight . impairment of the nutrition of the nervous 

 system, during the general emaciation which results from a wasting dis- 

 ease> or during that more gradual decline of the bodily vigour which is 

 consequent upon advancing age, is a phenomenon which strongly marks 

 it out as the part of the body, to the maintenance of whose integrity 

 everything else is subservient ; and this is still more remarkably shown 

 in the phenomena of starvation, in which state, notwithstanding the dis- 

 appearance of the whole of the fat, and the reduction of the weight of 

 the body in general by about 40 per cent., the nervous system appears 

 to lose little or none of its substance ( 117). 



3. Of Death, or Cessation of Nutrition. 



628. The general cessation of the Nutritive operations, in Death, 

 usually depends, as formerly explained ( 65), upon the cessation of the 

 supply of Nutriment, in consequence of the stagnation of the Circulating 

 current; and this stagnation may result from the direct operation of 

 three causes ; namely, failure in the propulsive power of the Heart, 

 or Syncope, obstruction to the flow of blood through the pulmonary 

 capillaries, consequent upon a deficient supply of air, or Asphyxia, 

 and a disordered state of the blood itself ( 534), which at the same 

 time weakens the power of the heart, and prevents the performance of 

 those changes in the systemic capillaries, which afford a powerful 

 auxiliary to the circulation ; a mode of death, for which the term Ne- 

 crcemia has been proposed. Each of these conditions may be dependent 

 upon a variety of remote causes, which cannot be here particularized. 

 But it is evident that, when either one of them has been established, the 

 nutritive processes must speedily cease, although they may continue for 

 a short time at the expense of the blood in the capillaries of the part. 

 The cooling of the body is another cause of their cessation ; and this 

 is one reason why molecular death (or the death of the individual organs 

 and tissues) follows so much more closely on somatic death (or the ces- 

 sation of the circulating and respiratory functions), in warm-blooded 

 than in cold-blooded animals. In either case, however, the solid tissues 

 may preserve for a time their independent vitality ; and changes may 

 take place in them, which indicate the continuance of their nutritive 

 actions to a certain extent, even when they have been disconnected from 

 the body. There are undoubtedly cases, however, in which the loss of 

 vital power is as complete and immediate in the solids as in the fluids ; 

 the want of ability to avail themselves of nutriment being as decided in 



