IQO 



LIGHT AND THE BEHAVIOR OF ORGANISMS 



toward it, and if then exposed to lateral illumination of a 

 lower intensity it seldom turns toward the source of light 

 at all, and orientation is direct.^ 



TABLE VI 



How are these results to be explained? It is ordinarily 

 supposed that the higher the illumination the more direct 

 the orientation in such organisms as fly larvae. The results 

 above indicate the opposite to be true. Have these crea- 

 tures the power of differential response to localized stimu- 

 lation, as the final results recorded in the table seem to 

 indicate ? 



During the normal process of locomotion, as already 

 stated, the larvae alternately swing the anterior end slightly 

 to the right and left at the same time that they thrust this 



^ The variable results recorded in Table VI show very clearly the im- 

 portance of studying reactions under different conditions, and also that 

 statistical results in the study of reactions may be very misleading. This is 

 particularly true in case of organisms which readily become acclimatized, 

 as the blowfly larvae do. If the larvae are exposed to direct sunlight half 

 an hour or so they frequently lose all power of response to lower intensities 

 and sometimes respond no longer even in direct sunlight. 



