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WILLIAM L. DOLLEY, JR. 



average angle of +9.6 degrees and then a little later under the 

 same conditions make an average angle of +21.6 degrees? This 

 difference is probably due to the fact that before the first test 

 the organism had not been tested experimentally at all. Before 

 the second series of trials it had just been tested in intermittent 



FIG. 7. Paths of a specimen of Vanessa (butterfly 25) showing the effect of 

 previous experience on its reactions in a field of continuous light composed of two 

 horizontal beams crossing at right angles. (Reduced by three-fourths.) Ar- 

 rows to the left in A and in B, direction of rays of continuous light of illumina- 

 tion, 14 m.c. ; arrows below in A and in B, direction of rays of continuous light of 

 illumination, 3.5 m.c. Arrows to the left in C, direction of rays of intermittent 

 light of flash-frequency of 30 per second produced by disk with one-fourth re- 

 moved. Arrows below in C, direction of rays of continuous light. Illumination 

 in each beam in C, 3.5 m. c. Figures have same significance as in preceding figures. 

 In A and B "plus" indicates deflection toward stronger light; "minus," toward 

 weaker light. In C, "plus" indicates deflection toward intermittent light; 

 "minus," toward continuous light. Conditions in A and in B were exactly iden- 

 tical except that the butterfly had not been tested experimentally before the trials 

 in B. It was however given the trials presented in C immediately before making 

 the paths reproduced in A. Note the difference between the paths in A and in 

 B. This difference is due to the fact that this organism in A was reacting, in part 

 at least, to conditions which had ceased to exist, i.e., to the conditions to which it 

 had just been reacting in C. 



