REACTIONS TO LIGHT IN THE EARTHWORM. 



The figures illustrate certain features of the worm in the extended and in the con- 

 tracted state. The states of extension and contraction represented are not the most 

 complete possible. 



FIGS. I and 2 are sagittal sections of the first five segments of an extended and a 

 contracted worm respectively. (<?) body wall, () everted buccal cavity slightly 

 protruding, which is used as a proboscis. It is to be noted that the first segment, 

 which is the most sensitive to light, is partly inrolled in Fig. 2 



FIGS. 3 and 4 are sections of the dorsal epithelium of the first segment of an ex- 

 tended and contracted worm respectively in the same plane as the last. 



FIGS. 5 and 6 give sections of epithelium in the extended and contracted condi- 

 tion. (/. f.) light cell. 



