2 9 o THE HUMAN SPECIES 



to me to be the most important. Darwin explains this by 

 saying that if a mental state is produced which is opposed by 

 certain purposeful associated movements, the inclination is ex- 

 cited to exhibit movements of a directly opposing nature. He 

 quotes as striking examples an angry or peaceful man, an angry 

 and a friendly dog or cat. (In an angry dog the ears point 

 forwards, in a peaceful dog backwards, and vice versa in cats.) 



The third principle he terms direct action of the nervous 

 system, independent of the will, and to a certain extent inde- 

 pendent of habit In man and animals, this includes the 

 muscle-tremor of fear, of great anger or extreme joy, the beat- 

 ing heart of terror or surprise, the staring eyes of horror. The 

 great anthropoids display very similar mimetic movements to 

 men, because their facial muscles are practically the same (Owen,. 

 Proc. Zool. Soc., 1830). 



Will. A gradual evolutionary scale can be traced out as 

 regards the will. The simplest manifestations of the will are 

 the reflexes, i.e., the elementary expressions of unconscious 

 psychical activity which result from the connection of sensation 

 and movement. The response of the whole protoplasm of a 

 unicellular protist to an external stimulus is a reflex movement. 

 Higher in the scale come those simple metazoa in which there 

 is direct reflex connection between a sensory-cell and a motor- 

 cell. Advancing a step higher we find joined to these two cells 

 a third "ganglion-" cell which is the seat of unconscious reason- 

 ing processes, as seen in most of the Invertebrates. In the 

 highest evolutionary forms, and among the Vertebrates gener- 

 ally, the reflex organs consist of the sensory and motor-nerve 

 fibres with two ganglion-cells intervening, one sensory and the 

 other motor ; by these means not only reflex, but also conscious, 

 movements are performed. Haeckel and the other supporters 

 of the monistic theory regard the conscious will of the higher 

 Vertebrates and man as a gradual development from the psychic 

 reflex activity ; they distinguish, however, two processes : (a) 

 primary reflex actions, or those which have never reached the 

 stage of consciousness in phyletic development, and thus pre- 

 serve the primitive character in the higher animals by trans- 

 mission from the lower forms ; (b) secondary reflex actions, i.e., 

 those which were conscious voluntary actions in our ancestors 

 but which afterwards became unconscious from habit or the 



