190 IOWA ACADEMY OF SCIENCES. 



He adopts the "wave theory of consciousness." The crest 

 of the wave is the focal point of consciousness. The slopes 

 of the wave are marginal and represent elements which, 

 although not focal, are still dimly within the field of conscious- 

 ness. They are sub-conscious. It will be seen that that which 

 is marginal at one instant becomes focal with the advancing 

 wave and is for a season again marginal as the wave passes 

 forward. 



It will be noted that the wave of consciousness is continuous 

 and this continuity of consciousness is what Morgan calls mind. 



The following canon of interpretation is enunciated by this 

 writer as a law that must be followed in interpreting psychical 

 phenomena other than our own, particularly non-human psy- 

 chical activities. 



"In no case may we interpret an action as the outcome of an 

 exercise of a higher psychical faculty, if it can be interpreted 

 as the outcome of the exercise of one which stands lower in the 

 psychological scale. ' ' 



We shall have occasion to discuss this canon further on. I 

 will simply remark in passing that it forms the main line of 

 contention in the correspondence between Professor Morgan 

 and myself. 



The following definitions of terms are the ones adopted by 

 Morgan, and indicate the sense in which the words are used in 

 this paper. Only such terms as are necessary to the discussion 

 need occupy our attention at pre ent. 



An instinctive act is a sub-conscious motor response to a 

 stimulus and precedes experience. Example, a newly hatched 

 chick will at once begin picking at small objects on the ground. 

 Newly born kittens will spit at a dog. 



Intelligent action is one based on previous experience. 

 Example, the young chick will after a little experience pick at 

 small seeds and refuse to pick at grains of sand. Young kittens 

 will not notice a dog with which they are acquainted, but will 

 spit at a strange dog. 



Association of ideas may be explained by again referring to 

 the wave theory of consciousness. 



When in past experience the wave has passed through a given 

 series involving a number of sense impressions, any one of 

 those sense impressions received on a subsequent occasion may 

 start again the same wave and cause the same, or some of the 

 same, impressions to again be present in consciousness. And 



