476 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



which molar motion is not produced from within, and 

 sensation is impossible. In popular language the one 

 class of energies tends to life ; the other to death. 



Herbert Spencer has defined evolution as a process 

 of "integration of matter and dissipation of motion"; 1 

 "the absorption of motion and the diffusion of matter" 

 he terms dissolution. If by evolution Mr. Spencer 

 referred only to that of inorganic bodies and masses, 

 his definition must be accepted ; but the evolution of 

 organic bodies, since it has proceeded in a direction 

 the opposite of the inorganic, cannot be so character- 

 ized. Organic evolution has passed beyond the do- 

 main of the inorganic, and the terms applicable to the 

 latter process cannot be correctly applied to the former. 

 In organic anagenesis there is absorption of energy; 

 dissipation of energy is only known in the functioning 

 of organic structures, which is catagenetic ; not in 

 their progressive evolution, which is anagenetic. 



Huxley, in a lecture delivered in I&54, 2 remarks : 

 "Tendency to equilibrium of force and permanency of 

 form then are the characters of that portion of the 

 universe which does not live, the domain of the chem- 

 ist and the physicist. Tendency to disturb existing 

 equilibriums, to take on forms which succeed one 

 another in definite cycles, is the character of the living 

 world." In the letter to Professor Tyndall, prefatory 

 to the volume Lay Sermons and Addresses, in which this 

 essay appeared, Huxley says: "The oldest essay of 

 the whole, that on ' The Educational Value of the 

 Natural History Sciences,' contains a view of the dif- 

 ferences between living and not-living bodies, which I 

 have long since outgrown." Whatever might have 



1 First Principles, ed. II., 1873, p. 542. 



2 Lay Sermons and Addresses, 1880, p. 75. 



