IOWA ACADEMY OF SCIENCES. 193 



to leave it in order to go to the drain on account of a mere 

 unreflective association of the idea rabbit with the idea "drain. " 

 That he did not in a true sense know why he went. That he 

 did not focus the therefore as a result of his past experience 

 and his knowledge of the short cut. 



No matter how apparently conclusive may be the evidence 

 that an animal has reasoned in a given instance Professor Morgan 

 will refer it all to sense experience, as in the case cited. 

 Indeed, I do not see how a human being could, without lan- 

 guage, give evidence of reason that could not by a similar 

 course of logic, or rather hypothesis, be referred to sense 

 experience. 



I cannot help thinking that Professor Morgan has fallen into 

 two serious errors, the first of which is the adoption of the canon 

 of interpretation before referred to. Let us state this canon 

 again : 



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

 the 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." 



My objection to this law of interpretation may be briefly 

 stated as follows: "Where two organisms are so very much 

 alike in anatomy, histology, physiology, embryology, etc., as 

 are man and the anthropoid, where there is strict homology in 

 so many thousands of particulars, the assumption is that this 

 homology extends to mental phenomena which are apparently 

 alike." Mr. Morgan in a recent letter explicitly agrees to 

 this statement, and adds: "For this reason I believe that the 

 mental phenomena of men and brutes are continuous and like 

 in kind. " I am so far unable to reconcile this last statement 

 with the trend of his argument in the work referred to above, 

 and especially in the following statement: "And I believe that 

 the extraordinary difference between men, even the lowest, and 

 animals, even the highest, is due to the introduction of the new 

 factors involved in the perception of relations and conceptual 

 thought. ' ' 



It seems to me that we would be more apt to arrive at a just 

 conclusion if we should adopt some such law of interpretation 

 as the following: 



When judgment is to be passed in the psychological activi- 

 ties of animals morphologically and physiologically like men 

 in thousands of particulars, it is fair to conclude that this like- 



