ACKNOWLEDGMLIJTS . 



The writer's heaviest obligation is to Irofeasor John 

 B. Watson, director of the Psychological Laboratory of The 

 Johns Eopkins University, without whose unsparing suggestions 

 and criticisms, the v>rork could not have been brought to a 

 STiccesaful conclusion. 



Dr. Knight Dunlap , Associate Professor of Psychology 

 at The Johns Eojkins University, offered much needed assist- 

 ance in the handling of the data. 



Dr. Gardner C. Basset, of the Pittsburgh University, 

 gave valuable suggestions regarding technique and method. 



Dr. Henry H. Donaldson, director of The Wistar Insti- 

 tute, furnished practically all of the rats used for breed- 

 ing puri OSes as well as a few of those employed in the ex- 

 perinent, and was most helpful in suggestions throughout 

 the experiment. 



Dr. Shinkiski Eatai prepared anatomical data for each 

 rat used in the experirrent, which cannot be adequately 

 handled in this discussion, and which will probably be taken 

 up in a separate jublication to aj.pear later. 



