30 EX VIRIBUS VIVIMUS. 



potential longevity, or what appears to belong to 

 that term, as above explained, will be meant. 



5. Inherent Death. 



Let us now parenthetically enquire as to this 

 inherent cause of death — this something in the or- 

 ganism which, more clearly than the other structures 

 and properties of the organism, limits life. We say, 

 ' more clearly,' for it is impossible to regard what 

 was ascribed to the ' milieu,' ' environment,' or ' ex- 

 ternal agencies,' without remembering that they have 

 their correlatives in the organism itself. 



How is it that absolute potential longevity is made 

 to have a limit by heredity t How is it that natural 

 decay is hereditary as to time and effect .' The whole 

 subject of the hereditary transmission of specific cha- 

 racters has been recently treated of by Mr. Darwin 

 in his volumes on 'Animals and Plants under 

 Domestication,' and the ingenious theory of Pan- 

 genesis started to explain and collect all these pheno- 

 mena under one head. Though Mr. Darwin does not 

 allude especially to seniHty, he mentions at length 

 periodic developments agreeing as to their time of 

 appearance in both parent and offspring. The theory 

 of Pangenesis is thus stated : ' I assume that cells 

 before their conversion into completely passive or 

 "formed material," throw off minute granules or 

 atoms, which circulate freely throughout the system, 



