Somatic death or death of the individual takes place immediately on the permanent failure to function of any one of the three indispensable organs, the integrity of which is essential to life; namely, the organs of the respiratory, the circulatory or the nervous system.
Molecular death or death of the tissues may not ensue immediately, because certain tissues are able to remain viable for variable lengths of time, on the nutritive material stored within the cells or surrounding them. The period of survival is also dependent on the resistance of the cells, the readiness of bacterial invasion and the presence of destructive enzymes. It may be possible, by several methods, to prolong further the life properties of those tissues which are able to survive.
By the first method, so well exemplified in tissue culture, the necessary nutritive materials may be artificially supplied. It has thus been possible to keep a