54 NATURE AND OBJECTS OF PHYSIOLOGICAL SCIENCE. 



perties depend upon their continual regeneration by the nutritive opera- 

 tions. Hence we have no difficulty in accounting for the Death of the 

 whole system, on the cessation or serious disturbance of any one impor- 

 tant function ; for any such check or change must suspend or disorder 

 the nutrient processes, in such a degree that they can no longer main- 

 tain the normal constitution of the several tissues. But as there is a great 

 variety in the rapidity of the decomposition of the tissues, when the 

 act of nutrition is suspended, so do we witness a corresponding variety 

 in the duration of their vital properties, after that permanent severance 

 of the chain of functions, which is distinguished as somatic death, i. e., 

 the death of the body as a whole. It is by the Circulation of the Blood, 

 that the connexion of the different functions is essentially maintained ; 

 that fluid being not only the material for the nutrition of the tissues, but 

 in many cases supplying also the stimulus to their activity. Hence 

 with the permanent cessation of the Circulation, somatic death must be 

 regarded as taking place. 



66. Yet after this, we observe that vitality lingers in the tissues ; and 

 that it departs from them only as they lose their proper composition. 

 Thus we find that, although the Nervous centres cannot originate the 

 stimulus necessary to produce Muscular contraction, after the Circula- 

 tion has ceased, yet the Nervous fibres can convey such a stimulus, long 

 after somatic death ; so that contractions may be excited in muscles by 

 the application of galvanism, or of mechanical or chemical stimulants, 

 to the trunks that supply them. The molecular death of the Nervous 

 tissue, therefore, has not yet taken place. After a time, however, this 

 power is lost ; the tissue no longer exhibits its distinguishing vital pro- 

 perties ; and incipient decomposition and change of structure manifest 

 themselves. Yet for some time after this, the Muscular tissue, especially 

 in a cold-blooded animal, continues to possess its peculiar contractility ; 

 for contractions may be excited in it, by stimuli directly applied to itself, 

 long after the nerves have ceased to convey their influence. Sometimes, 

 indeed, the contractility of muscle endures, until changes in its struc- 

 ture and composition become evident to the senses ; thus the heart of a 

 Sturgeon, removed from the body, and hung up to dry, has been known 

 to continue alternately contracting and dilating, until the movement pro- 

 duced a crackling noise, in consequence of the dryness of the texture. 

 Again, there is evidence, that various processes of nutrition and secre- 

 tion may go on, for some time after somatic death, and even after the 

 removal of the organs from the body, provided a sufficient quantity of 

 blood remains in them ; and the blood itself retains its vitality, so as 

 not to coagulate, whilst contained in the vessels of tissues still living. 



67. Hence it is, that parts which have been completely separated from 

 the body may often be reunited with it, if they were previously in a 

 healthy state, and too much time have not elapsed ; thus, there are many 

 cases on record, in which fingers, toes, noses, or ears, that have been 

 accidentally chopped off, have been made to adhere and grow as before, 

 by bringing the cut surfaces into contact, even some hours after their 

 severance. It is evident, then, that the parts so severed cannot have 

 lost their vitality ; since no treatment could produce union between 

 a dead mass and a living body. And we are fully justified in assuming, 



