OBSERVATIONS OF THYONE BRIAREUS. 



275 



inclined toward the left, the anterior end of the body being placed 

 toward the window in the first case and away from it in the second. 

 The dish was then inclined toward the right and the same pro- 

 cedure repeated. The distance from the center to the edge of 

 the dish was fourteen centimeters and directions which the different 

 individuals took in reaching the latter are shown in Table I. 

 These results do not show any strongly geotropic tendency and 

 the next step would naturally have been to test individuals on an 

 inclined surface with the light coming from above or to make 

 similar tests in total darkness but lack of time prevented such 

 experiments being carried out. 



Table I. 



Deflection in moving fourteen centimeters away from the light on a plane surface 

 inclined 5.6° at right angles to the direction of the light rays. 



3. Chemical Stimuli. — No extensive experiments to test reac- 

 tiveness to chemical substances were made. It was hoped, how- 

 ever, that positive responses might be obtained by using food 

 substances, but repeated experiments with fish and crab extract, 

 crushed eel-grass and scrapings from the surface of the mud were 

 without results. The reactions which resulted when the water 

 became foul were doubtless due to chemical stimuH, In this case 

 individuals extended the posterior end of the body until the cloa- 



