FUNDAMENTAL FACTS 13 



can be shown that Infusoria, Ccelenterates, and 

 worms do not possess a trace of associative memory. 

 Among certain classes of insects (for instance, 

 wasps), the existence of associative memory can be 

 proved. It is a comparatively easy task to find out 

 which representatives of the various classes of ani- 

 mals possess, and which do not possess, associative 

 memory. Our criterion therefore might be of 

 great assistance in the development of comparative 

 psychology. 



7. Our criterion puts an end to the metaphysical 

 ideas that all matter, and hence the whole animal 

 world, possesses consciousness. We are brought to 

 the theory that only certain species of animals possess 

 associative memory and have consciousness, and that 

 it appears in them only after they have reached 

 a certain stage in their ontogenetic development. 

 This is apparent from the fact that associative 

 memory depends upon mechanical arrangements 

 which are present only in certain animals, and 

 present in these only after a certain develop- 

 ment has been reached. The fact that certain ver- 

 tebrates lose all power of associative memory after 

 the destruction of the cerebral hemispheres, and 

 the fact that vertebrates in which the associative 

 memory either is not developed at all or only slightly 

 developed (e. g., the shark or frog) do not differ, or 

 differ but slightly, in their reactions after losing the 

 cerebral hemispheres, support this view. The fact 

 that only certain animals possess the necessary 



