8o EX VIRIBUS VIVIMUS. 



generative outlay. Most of these forms die on re- 

 production. Taenia does not die at once, because 

 of its tertiary aggregation; that is to say — it is 

 separated into a number of joints, which, one by 

 one, come to maturity and die, whilst new joints 

 continue to grow from the head. 



These are some of the most striking inductive 

 verifications which the collected statements furnish ; 

 others are to be found by a further examination of 

 the list. 



1 1. Other Relations of Longevity. 



There seem to be some minor modifications of 

 the terms ' evolution ' and ' expenditure' which affect 

 longevity, and which do not strike us at once as 

 coming under those heads, and yet are very plainly 

 influential in the result. How difficult it is to get 

 clear views in the intricacies of such a problem as 

 the one before us, we may let Mr. Spencer say, who 

 shews, in his chapter on the Inductive Verification 

 of the Laws of Multiplication, the frequency of com- 

 plications which can only be dealt with by the use 

 of the phrase 'cseteris paribus' as a continual quali- 

 fication. 



Animals which feed on large masses of food, of 

 great concentration — as, e. g. other animals, or special 

 fruits and portions of trees — are longer lived than 

 those feeding on diffused and widely-spread food, 

 as the lower sorts of vegetable growth and decaying 



