46 EX VIRIBUS VIVIMUS. 



state. To the period of dissolution belong those 

 slow senile changes, or that rapid exhaustion of 

 power, which it is clear from the preceding section 

 depend on the period of growth, in large measure 

 as to their length, but which are also affected by- 

 external agencies, which will be referred to again. 

 The period of reproductive activity is a variable 

 quantity according to the case, in some lasting but 

 a brief day or hour of the whole life, whilst in other 

 organisms, for certain definite objects, it may be pro- 

 longed over a considerable time, recurring at intervals. 

 This period does not seem to depend directly on 

 the period of growth at all, but it is distributed to 

 organism with regard to other and special conditions. 



7. High Individuation favours Longevity. 



Having seen; then, that the period of evolution 

 is a very important item in longevity, since (p. 44) 

 the period of dissolution depends directly on it, 

 as to duration, we are in a position deductively 

 to make the proposition that potential longevity 

 varies with, or is favoured by, high evolution, if it 

 be admitted that high evolution, i. e. complex struc- 

 ture and large bulk, both or either, are identical with 

 evolution occupying long time. A few considerations 

 will prove that this is admissible. You cannot have 

 mere growth , of bulk without time, as is obvious 

 from general facts; the very word 'grow' implies 



