REAL AND APPARENT DEATH. 403 



discontinued beyond a brief interval without fatal consequences, the 

 latter such as may be suspended or even destroyed without involving 

 general dissolution. Thus, although eight is important to comfort, it 

 may be lost without affecting vitality ; the hepatic function may be 

 vicariously performed ; even the renal secretion may be suspended for 

 a considerable period without death : but the complete cessation of 

 any of the essential functions of circulation, innervation, or respiration 

 must be speedily followed by such a result. By the circulatory forces, 

 a constant flow of blood is directed to and from all the parts ; by the 

 nervous system, an alternating effect is produced on the tissue-elements, 

 whereby at one time they assimilate, at another disintegrate ; by the 

 respiratory apparatus, certain of the resultant products are incessantly 

 eliminated. These three complemental functions are so interdepen- 

 dent that the complete interruption of either necessarily leads to 

 arrestment of all, and consequent death. 



Human blood is of a highly complex nature, as through it the 

 textures receive all the materials adequate to their continued mainte- 

 nance and repair. Its chemical composition is never definite, varying 

 in different individuals and in the same individual on different occa- 

 sions. The relative uniformity, however, of some of its physical char- 

 acters is indispensable to its vital efficiency. It is semi-solid, contain- 

 ing innumerable white and red corpuscles, the latter constituting nearly 

 one half its mass. The absolute number of these corresponds with 

 the degree of general vitality ; their local aggregation fluctuates with 

 varying contingencies. 



This fluid is the seat of two distinct modes of motion a sensible 

 circulation through the heart and vessels, and a subtiler interchange 

 with tissue-elements. Several causes conspire toward its circulatory 

 mass-motion, the heart's action being a sine qua non. The molecular 

 motions being invisible, an explanation of their modus operandi must 

 be partly hypothetical. There are, however, certain associated phe- 

 nomena admitting of direct observation under certain circumstances 

 which serve to throw light on the physico-vital relations of the blood. 

 Thus, besides its general distribution, it is subject to local variations 

 in the total quantity of its mass, and in the relative proportion of its 

 various constituents. As there are means of artificially exciting pre- 

 ternatural -activity of the circulation to a recognizable extent, in parts 

 open to observation, during the minimum degree of vitality, such a 

 possibility affords a reliable method of infallibly deciding in any 

 particular case as to the existence or non-existence of this vital 

 process. 



Tissues are divisible into vascular and non-vascular, according to 

 the mode and extent of their nutritive supply. The latter, being des- 

 titute of capillaries, receive their nourishment from the neighboring 

 vessels by endosmosis. The former are pervaded by those minute 

 vessels, which admit red corpuscles in a lesser or greater number, ac- 



