360 ANIMAL NATURE AS A WHOLE. [iii. 



function, separation of the body and soul can only take place, 

 when those parts of the brain are involved which constitute 

 the centre of its animal-sentient forces. But inasmuch 

 as these are scattered throughout the brain, often injury 

 of the cerebral medulla only destroys a certain class of animal- 

 sentient forces, and others not naturally subordinate to them, 

 remain uninjured. Thus, it is possible in injuries of the head, 

 or in old age, that one kind of external sense, or the memory, 

 understanding, judgment, &c., may be enfeebled or abolished, 

 while other faculties are unaffected, v. By whatever entirely 

 prevents those impressions, which put the primary vital forces 

 into action, or maintain them in action, in so far as the animal- 

 sentient forces of the brain (which are subordinate to them) 

 are abolished (716). 



727. All these various kinds of death are usual in nature. 

 Often mental death precedes mere animal dissolution; often 

 both occur at the same time ; but in every case, traces of mere 

 animal life remain after the soul is separated from the body. 

 When all conceptions are abolished, and all sentient actions have 

 ceased, the body still manifests signs of the vis nervosa ; peri- 

 staltic motion continues, the heart makes a few feeble strokes 

 (the right ventricle retaining the power of motion the longest), 

 and the muscles are still irritable. Even when all other tissues 

 are no longer capable of stimulation, the heart's action may be 

 renewed by external impressions, so that to this extent we may 

 consider with Haller (Physiology, § 961), that the moment the 

 heart loses its irritability is the moment of complete animal 

 death. That the moment of interruption of the heart's action 

 is not that moment, is manifest from what has been already 

 stated (711 — 721). Undoubtedly, every trace of the vis nervosa 

 disappears as soon as the parts become cold, or deprived of 

 moisture. 



728. After absolute death comes the end of the remaining 

 part of the entire nature of the dead body, that is, of the 

 organic, mechanical, and physical forces, and is termed putre- 

 faction. It resolves all the animal machines, — the brain and 

 nerves, — together with all the other components of the animal 

 organism, into their primary elements. 



END OF "PRINCIPLES OF PHYSIOLOGY." 



