PSYCHOLOGY 265 



phylogeny in a form easy to grasp, for he by logical and 

 exact steps traced the development of the nerve-elements as 

 channels of psychic activity. There is no need to be surprised 

 at his representing the primitive " cell-mind " as present in the 

 unicellular organisms. Relying as he does upon the support 

 of Max Venvorn's Psycho-physiological Studies of the Protists, 

 who came to the conclusion that " the psychic phenomena 

 of the Protista form a bridge that connects the chemical 

 processes of the inorganic world with the psychic life of the 

 highest animals ; they represent the germ of the highest 

 psychic phenomena of the metazoa and of man ". 



A higher development is found in the infusoria which 

 are capable of movement and (above all) of unconscious 

 sensibility ; indeed the great cell-nucleus (tneganncleus] is 

 regarded by some scientists as a differentiated organ of 

 psychic activity. From the unicellular organisms, the cell- 

 mind proceeds to the cell-community (i.e., the blastula-cell), in 

 which, in addition to the cell-minds of the individual cells, there 

 is the communal mind of the entire colony. 



This finally makes way for the tissue mind in the organs of 

 the metazoa, where each single cell has its own sensation and 

 movement, and each tissue and each organ composed of a 

 number of homogeneous cells has its special irritability. 



Those metazoa which possess no differentiated nerves have 

 still a very deep-seated mind-life. In their lowest forms they 

 remind us of the two primitive embryonic layers of the higher 

 metazoa, from the outer layer of which, the ectoderm, are de- 

 veloped the sense-organs and the nerves ; so these lowest 

 metazoa represent the earliest form from which the whole 

 series of higher animals with nerves have evolved. The free 

 swimming medusae, unlike the stationary hydropolyps from 

 which they are developed, possess sense-organs, nerves and 

 ganglia which, on the one hand, are the means of communica- 

 tion between the sense-organs and the muscles, and on the 

 other hand, are the seat of the perceptions and sensations. 

 The higher we proceed in the Invertebrates the more highly 

 developed are the psychic functions until we reach the 

 cephalopods and brachiapods which, in spite of the small di- 

 mensions of their ganglia, possess a degree of intelligence and 



