82 L. W. SACKETT 



21. Other memory tests of the porcupine show better reten- 

 tion where motor or kinaesthetic factors are characteristic of 

 the response than where the same general motor response fol- 

 lows a choice of sensory stimuli, i.e., ability to thread a maze 

 and operate a puzzle-box is retained better than ability to 

 choose between the forms and the brightness boxes. 



Conclusion. — It has been the policy of the paper to be con- 

 servative at all times in evaluating the material and particu- 

 larly so in regard to the qualitative results. It has seemed, 

 throughout the study that occasional faint glimpses, or fore- 

 gleams, have been caught of a broader conception of the animal 

 mind which may sometime, by some master thinker be evolved. 

 The present state of the science is hardly even that of a mosaic. 

 Methods, even, are as incomparable as results. Yet there is. 

 hope for the fulfillment in this field, of the prophecy of Presi- 

 dent Hall (20) in the wider field of evolutionary psychology. 

 "The material for perhaps the most majestic structure yet 

 reared by science is already quarried. The need of, and call 

 for, a master builder in this field must, ere long, produce the man." 



In making this study I have been indebted to all who have 

 in any way come in contact with the work. To President G. 

 Stanley Hall for the liberal financial support wliich Clark Uni- 

 versity has given ; to Dr. James P. Porter for his constant 

 oversight, earnest co-operation and valuable suggestions; to 

 Dr. Wm. H. Burnham for assistance in planning problems and 

 inteipreting results ; to Dr. J. W. Baird for helpful criticism 

 of the more technical parts of the discussion. Far more than 

 to anyone else, I owe acknowledgment to my wife who has been 

 more than an assistant in the work. Proper recognition would 

 involve the details of whole sections of the study, comprising 

 thousands of tests wherein I have personally taken little part, 

 beyond general daily oversight, from the time the experiment 

 was fully planned to the final e\'aluation of results after all 

 tests had been made. In addition to this, most of the drudg- 

 ery of final copying, arrangement of bibliography, drawing of 

 curves, etc., must be attributed to the same co-operation. I 

 shall, of course, assume all responsibility for crudities in the 

 methods, errors in the work, naivete in the interpretation, or 

 lack of clearness in the exposition. 



