224 BIOLOGY OF DEATH 



somatic cells of the body, however much differentiated, 

 are also potentially immortal; but the conditions neces- 

 sary for the actual realization of the potential immor- 

 tality are, in the nature of the case, as has been shown 

 by the brilliant researches of Leo Loeb, Harrison and 

 Carrel on tissue culture, such as cannot be realized so 

 long as these cells are actually in and a part of the higher 

 metazoan body. The reason why this is so, and why in 

 consequence death results in the metazoa, is that, in such 

 organisms the specialization of structure and function 

 necessarily makes the several parts of the body mutually 

 dependent for their life upon each other. If one organ 

 or group, for any accidental reason begins to function 

 abnormally and finally breaks down, the balance of the 

 whole is upset and death eventually follows. But the 

 individual cells, themselves, could go on living indefinitely, 

 if they were freed, as they are in cultures, of the neces 

 sity of depending upon the proper functioning of other 

 cells for their food, oxygen, etc. 



So then we see emerging, as our first general result, 

 the fact that natural death is not a necessary or inevit- 

 able consequence of life. It is not an attribute of the 

 cell. It is a by-product of progressive evolution the 

 price we pay for differentiation and specialization of 

 structure and function. 



This first result indicates logically, in any particu- 

 lar organism such as man, the great importance of 

 a quantitative analysis of the manner in which dif- 

 ferent parts of the body break down and lead to death. 

 Such an analysis, carefully worked through, demonstrates 

 that this breaking down is not a haphazard process, but 

 a highly orderly one resting upon a fundamental biolog- 

 ical basis. The progress of the basic tissue elements 



