CONSCIOUSNESS IN EVOLUTION. 399 



activity over that necessary to unconscious activity is well known. 

 It is thus evident that organization renders consciousness unne- 

 cessary, GO long as external conditions are unchanged, and most 

 probably a degree of fixity may be attained which renders con- 

 sciousness impossible. The history of the evolution of animal 

 types is apparently an illustration of this truth. The relations 

 of the divisions of the animal kingdom are those of the limbs, 

 branches, and trunk of a tree. Although the termini of the 

 branches are successively nearer the root or starting-point as we 

 proceed from the apex downward or backward, yet the connec- 

 tion is not from end to end of these. To find this we pass down 

 the limb to its junction with the trunk, and trace the branches 

 from the axis outward. Thus with the branches of the animal 

 kingdom. Although the divisions Vertebrata, Mollusca, Echino- 

 dermata, etc., stand in an undoubted relation of succession to 

 each other, there is no connection between the highest representa- 

 tive of one and the lowest of another. It is the lower or less 

 specialized forms of each which exhibit the relationship. Thus, 

 among the articulates, the low group of the worms gives us con- 

 nection with the Mollusca above by BracMopoda, and the echino- 

 derms connect themselves with the Vermes by the less specialized 

 Holothurida. It seems highly probable also that the point of con- 

 tact of the Vertebrata with these is by one of the lowest divisions, 

 formerly regarded as molluscan, viz.: the Ascidia. The same 

 principle holds good within the great divisions. The most spe- 

 cialized orders of Mammalia are the Artiodactyla, higher Perisso- 

 dactrjla, the Carnivora, Quadrumana, and perhaps Cetacea ; but 

 the higher of these have not been derived from the lower. Mod- 

 ern investigations show that several of them have been derived 

 from a common type of mammals of the Eocene period, wiiich is 

 intimately connected with their lower forms, while wanting in 

 the features which give them their special characters. These two 

 illustrations serve to explain the universal law of zoological affin- 

 ity, and therefore of evolution. 



The conclusion derived from a survey of this field is, that 

 structure, like habit, when once established, is closely adhered to, 

 and that the movement of growth-force once determined or or- 

 ganized becomes automatic, i. e., independent of consciousness. 

 Therefore a type which reproduces itself automatically becomes 

 after a time so established as to be incapable of radical change, in 

 consequence of a molecular fixity which precludes it. Neverthe- 



