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BRADLEY M. PATTEN 



entered in the appropriate column, and the sum of the total minus 

 deflection and of the total plus deflection of the four trails is 

 entered in the net column. The sum of the plus and minus 

 deflections of a larva divided by the number of trails made gives 



10/9/'l3 



Fig. 6 Diagram to show the method of measuring trails. The lines xi/ and .c'//' 

 are drawn through the trails at the points reached — marked by the arrows — when 

 the side lights were turned on. The angle of deflection from this line is measured 

 by a protractor, P. The small figures near the arrows indicate the number of 

 wig-wag movements made when the side lights were turned on; 1st and 2nd refer 

 to the sequence in which the trails were run; No. 7 is the box number, which, in 

 combination with the date, gives the identification number of the larva. 



the average angular deflection of the larva. The mean of the 

 average deflections of a large number of individuals forms the 

 final quantitati\e expression of the response to a given set of 

 conditions. A study of this table shows that very few trails 



