The Intimate Causes of Old Age. 199 



vicarious action begins ; what we term " constitution " is 

 broken up and discordant action ensues. Most persons 

 die of this organic discord. 



A number of years ago, the startling statement was put 

 forward, that organic decline, ending in death, comes from 

 a progressive asphyxiation of the tissue cells ; that after 

 adult life, we slowly suffocate, from a thickening and 

 hardening of the membranes of the alveolar sacs of the 

 lungs, oxygen no longer passing freely in, nor carbon 

 dioxide out. The hardening of the alveolar membrane is 

 aggravated from impregnation by minute dirt particles in 

 respired air ; it being a well-established fact that the lungs 

 are progressively discolored from infancy to old age ; and 

 that the lungs of certain craftsmen, stone-workers, dry 

 grinders, and others, are very palpably thus impregnated. 



As a proximate cause of organic decline, there must be 

 something in this hypothesis, which will have to be 

 reckoned with in any future effort to alleviate the causes 

 of old age. But it can scarcely be said to go to the root 

 of the matter, and we are still left to inquire why other- 

 wise than by impregnation with visible particles of dirt, the 

 alveoli become hardened, lifeless sacs, impervious to gases, 

 instead of the living, pervious membrane of childhood. 

 And this leads to casual mention of a theory of old-aging, 

 suggested from this Laboratory in 1896, namely, the 



