356 ANIMAL NATURE AS A WHOLE. [m. 



are secreted and diffused (678); and the brain cannot be 

 active if the heart do not, in virtue of its primary vital 

 force, transmit the blood to it, so that the vital spirits may 

 be secreted. Further, the primary vital force of the heart is 

 inoperative, if the vital spirits do not flow to it, and if external 

 impressions be not duly received by it (678, 679). 



711. Firstly, complete death may take place when the heart 

 wholly ceases to act, and all the functions dependent on the 

 circulation are entirely abolished; so long, however, as the hearths 

 action continues, in however slight a degree, the animal still 

 lives ; or so long as the arteries maintain the circulation, which 

 may occur longer in the capillaries than in the larger vessels, 

 independently of the direct action of the heart ; or so long as 

 there is blood remaining in the brain, from which vital spirits 

 may be secreted ; or, so long as vital spirits remain in the nerves, 

 and render them capable of duly receiving impressions. It is 

 thus we can understand, why certain animals survive after the 

 heart's action has ceased, or even when that viscus has been 

 entirely removed from the body. 



712. Secondly, complete death may result from whatever 

 destroys the primary vital force of the brain, or of its analogue, 

 and prevents the secretion of the vital spirits, and their diffu- 

 sion through the entire system of animal machines; so soon 

 as the functions dependent thereon are quite abolished, the 

 animal is perfectly lifeless. If, however, the primary vital 

 force of the brain continues to act in the slightest degree, or 

 if there be any vital spirits remaining in the animal machines 

 after the removal or destruction of the brain, so that they are 

 capable of duly receiving impressions, the animal is not 

 absolutely dead. 



713. Thirdly, death is complete, when either both the primary 

 vital forces are abolished at once, or when the one is so arrested, 

 that the other is destroyed. So soon as the operations of one 

 or both cease entirely, the animal dies absolutely, because they 

 are mutually subordinate to each other. But if the centres of 

 one of these vital forces be removed from the body or destroyed, 

 without the other being entirely abolished, then death is not 

 complete. Such is the case in those animals in which the 

 arterial system keeps up the circulation for a lengthened period, 

 after removal of the heart ; or in those in which several points 

 of the nervous system secrete vital spirits, and thereby maintain 



