xiv CONTENTS 



CHAPTER VII 



PAGE 



THE MEANING OF EVOLUTION 245 



Argument. If we assume the existence of an evolutionary 

 process, the results of morphology, embryology, and palaeontology 

 ought to enable us to trace the directions followed during this 

 process. But these results are still so uncertain that they indicate 

 only a few main lines of transformism. Phylogenetic trees are 

 largely conjectural in matters of detail. Evolution has resulted in 

 the establishment of several dominant groups of organisms the 

 metatrophic bacteria, the chlorophyllian organisms, the arthro- 

 pods, and the vertebrates. Each of these groups displays certain 

 characters of morphology, energy-transformation, and behaviour ; 

 and a certain combination of characters is concentrated in each of 

 the groups. But there is a community of character in all organisms 

 which have arisen during the evolutionary process. The trans- 

 formation of kinetic into potential energy is characteristic of the 

 chlorophyllian organisms. The utilisation of potential energy, 

 and its conversion into the kinetic energy of regulated bodily 

 activity, by means of a sensori-motor system, is characteristic of 

 the animal. The bacteria carry to the limit the energy-transforma- 

 tions begun in the tissues of the plants and animals. Immobility 

 and unconsciousness characterise the plant, mobility and con- 

 sciousness the animal. Animals indicate two types of actions 

 intelligent actions and instinctive actions. Instinctive activity 

 involves the habitual exercise of modes of action that have been 

 inherited. Intelligent activities involve the exercise of modes of 

 action that are not inherited, but which are acquired by the 

 animal during its own lifetime, and are the results of perceptions 

 which show the animal that its activity is relative to an outer 

 environment. 



CHAPTER VIII 



THE ORGANIC AND THE INORGANIC ..... 289 



Argument. A strictly mechanistic hypothesis of evolution 

 compels us to regard the organic world, and the inorganic environ- 

 ment with which it interacts, as a physico-chemical system. All 

 the stages of an evolutionary process must therefore be equally 

 complex : they are simply phases, or rearrangements, of the 

 elements of a transforming system. The physics on which these 

 mechanistic hypotheses were based was that of a discontinuous, 

 granular, Newtonian universe, that is, one consisting of discrete 

 particle?, cr mass-points, attracting or repelling each other with 



