And here is suggested the need for supplementing this conception of evolving conduct. For besides being an improving adjustment of acts to ends, such as furthers prolongation of life, it is such as furthers increased amount of life. Reconsideration of the examples above given will show that length of life is not by itself a measure of evolution of conduct; but that quantity of life must be taken into account. An oyster, adapted by its structure to the diffused food contained in the water it draws in, and shielded by its shell from nearly all dangers, may live longer than a cuttle-fish, which has such superior powers of dealing with numerous contingencies; but then, the sum of vital activities during any given interval is far less in the oyster than in the cuttle-fish. So a worm, ordinarily sheltered from most enemies by the earth it burrows through, which also supplies a sufficiency of its poor food, may have greater longevity than many of its annulose relatives, the insects; but one of these during its existence as larva and imago, may experience a greater quantity of the changes which constitute life. Nor is it otherwise when we compare the more evolved with the less evolved among mankind. The difference between the average lengths of the lives of savage and civilized is no true measure of the difference between the totalities of their two lives, considered as aggregates of thought, feeling and action. Hence, estimating life by multiplying its length into its breadth, we must say that the augmentation of it which accompanies evolution of conduct, results from increase of both factors. The more multiplied and varied adjustments of acts to ends, by which the more developed creature from hour to hour fulfills more numerous requirements, severally add to the activities that are carried on abreast, and severally help to make greater the period through which such simultaneous activities endure. Each further evolution of conduct widens the aggregate of actions while conducing to elongation of it. § 5. Turn we now to a further aspect of the phenomena, separate from, but necessarily associated with, the last. Thus far we have considered only those adjustments of acts to ends which have for their final purpose complete individual life. Now we have to consider those adjustments which have to their final purpose the life of the species.