44 EX VI Ji IB US VIVIMUS. 



representing its condition in the same units being 

 respectively for the four years, 7, 13, 19, and 13, 

 whilst it descends to i in the fifth year. Now, for 

 comparison, suppose 9 units as the initial capital, and 

 the same relations of expenditure and profit, we shall 

 find that the diminution does not commence till the 

 fifth year, the growth thus continuing a year longer,' 

 the figures being 15, 24, 35, 36, and 33 respectively. 



These two cases, in which the quantities are of 

 course merely arbitrarily chosen for example, and 

 in which the ratio of expenditure and profit as to 

 increase is exaggerated, suffice to demonstrate the 

 principle, which may be appHed to organisms. It 

 is because the calf at birth is a much larger animal 

 than the lamb, having been carried longer by its 

 parent, who from her greater size could of course 

 give to the ofispring a greater proportionate amount 

 of living matter to commence life with, that the cow 

 lives longer than the sheep, or rather inherits a later 

 natural limit to life. The quality of the germinal 

 matter and many other conditions which have to be 

 provided for, in laying down such rules as this, by the 

 expression ' cseteris paribus,' must always be taken 

 into consideration. 



We have, then, seen reason to think that the dura- 

 tion of life, after growth is completed or coming to an 

 end, depends on the amount of living matter accumu- 

 lated during growth, and that this depends on the size 

 at birth, ceteris paribus. Thus it is that we may trace 



