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ROBERT M. YERKES 



Figure 3. — General plan for three sizes of reactive tendency apparatus. S, small apparatus; M, medium appa- 

 ratus; L, large apparatus. X, center of circles on arcs of which reaction boxes and outer alley walls are 

 placed; A, release box for small apparatus; B, release box for medium apparatus; C, release box for large 

 apparatus; D, E, F, alleys for small, medium, and large apparatus, respectively; 13, release door (the release 

 doors for the three sizes of apparatus are shown); 14, door between release box C and alley F. 



