70 Scientific Proceedings, Royal Dublin Society. 



Turning to the factor, " adaptation," we find that this also 

 must pre-suppose, in order to be explicable, some quality of 

 aggressiveness on the part of the organism. For adaptation in 

 this or that direction is the result of repulse or victory, and, there- 

 fore, we must pre-suppose an attack. The attack is made by the 

 organism in obedience to its law of demand ; we see in the adapta- 

 tion of the organism but the accumulated wisdom derived from 

 past defeats and victories. 



Where the environment is active, that is living, adaptation 

 occurs on both sides. Improved means of defence or improved 

 means of attack, both presuppose activity. Thus the reaction 

 with the environment, animate and inanimate, are at once the 

 outcome of the eternal aggressiveness of the organism, and the 

 source of fresh aggressiveness upon the resources of the medium. 



Asconcernsthe "survival of the fittest" (or "natural selection"), 

 we can, I think, at once conclude that the organism which best 

 fulfils the organic law under the circumstances of supply is the 

 " fittest," ^}:>60 facto. In many cases this is contained in the 

 common-sense consideration, that to be strong, consistent with 

 concealment from enemies which are stronger, is best, as giving 

 the organism mastery over foes which are weaker, and generally 

 renders it better able to secure supplies. Weismann points out 

 that natural selection favours early and abundant reproduction. 

 But whether the qualifications of the " fittest" be strength, fer- 

 tility, cunning, fleetness, imitation, or concealment, we are safe in 

 concluding that growth and reproduction must be the primary 

 qualities encouraged by selection. Inherent in the nature of the 

 organism is accelerated absorption of energy, but the qualifications 

 of the " fittest" are various, for the supply of energy is limited, 

 and there are many competitors for it. To secure that none be 

 wasted is ultimately the object of natural selection, deciding 

 among the eager competitors what is best for each. 



In short, all the facts and generalizations concerning evolution 

 must presuppose an organism endowed with the quality of pro- 

 gressive absorption of energy, and retentive of it. The continuity 

 of organic activity in a world where supplies are intermittent is 

 evidently only possible upon the latter condition. Thus it appears 

 that the dynamic attitude of the organism, considered in these 

 pages, occupies a fundamental position regarding its evolution. 



