QUANTITATIVE DETERMINATION OF LKiHT REACTIONS 239 

 TABULAR AND GRAPHIC STATEMENT OF RESULTS 



Having perfected a system of measuring the reaction of the 

 larvae to light, and established a fixed point of departure by 

 means of the experiments with equal, opposed lights, we were 

 able to attack the problem which actuated this work, namely, a 

 tabulation of the reactions to opposing lights of different in- 

 tensities, acting simultaneously on opposite sides of the animal. 



It seemed advisable to begin at a well defined difference of 

 intensity and work toward equality. Accordingly the apparatus 

 was set up for a difference of 50 per cent between the opposing 

 lights. By throwing glowers in or out of circuit, the absolute 

 intensity of the common source of light could be varied at will, 

 but however the source was varied, the relative intensity of the 

 opposed beams remained the same. The reactions were all 

 measured and tabulated as described in the preceding section, 

 but as it would be impracticable to reproduce in detail over 30 

 tables comprising the measurements of 3000 trails it has been 

 necessary to condense greatly the tabular statement of the 

 results. 



Table 4 was compiled from the reactions of larvae stimulated 

 on opposite sides by lights of a constant difference of 50 per cent. 

 The absolute intensities of the opposed beams (table 1) were 

 varied by using from one to five 220-volt Nernst glowers as sources 

 of light. Each column in the table shows the average response 

 of 25 larvae, each run four times. The average angular deflec- 

 tion of these 100 trails is taken as the measure of the aggregate 

 response to the special conditions. Table 4 is a condensation 

 from five tables such as table 2, each column in table 4 represent- 

 ing the "Average angular deflection" column of table 2. In 

 table 5 the statement of the measurements is still further con- 

 densed. By comparing tables 4 and 5 it will be seen that the 

 50 per cent column of table 5 corresponds to the "Averages for 

 100 trails" given at the bottom of table 4. Table 5, therefore, 

 including as it does similar summaries of the measurements at 

 all the other intensity differences used, is a tabular statement of 

 the final results of the whole series of experiments. 



