328 LIFE AND DEATH. 



anatomical elements would destroy and devour them 

 as soon as their vitality diminishes, and would take 

 their place. In the brain, for example, it would be 

 the phagocytes which, attacking the nervous cellules, 

 would disorganize the higher elements, incapable of 

 defending themselves. This substitution of the con- 

 junctive tissue, which only possesses vegetative pro- 

 perties of a low order, for the nervous tissues, which 

 possesses very high vegetative properties, results in 

 an evident breaking-up. The gross element of 

 violent and energetic vitality stifles the refined and 

 higher element. 



This expulsion is a very real fact. It constitutes 

 what is called senile sclerosis. But the active role 

 attributed to it by Metchnikoff in the process of 

 degeneration is not so certain. An expert observer 

 in the microscopic study of the nervous system, M. 

 Marinesco, does not accept this interpretation as far 

 as the senescence of the elements of the brain is con- 

 cerned. Diminution of the cell, the' decrease in the 

 number of its stainable granulations, chromatolysis, 

 the formation of inert, pigmented substances all 

 these phenomena which characterize the breaking-up 

 of the cerebral cells would be accomplished, according 

 to this observer, without the intervention of the 

 conjunctive elements, the phagocytes. 



The characteristic of extensive and progressive 

 process presented by death necessitates in a com- 

 plex organism, which is a prey to it, the existence 

 side by side of living and dead cells. Similarly, in 

 the organism which is growing old, there are young 

 elements and elements of every age side by side with 

 senile elements. As long as the disorganization of 

 the last has not gone too far, they may be rejuvenated. 



