42 Instinct and Intelligence 



municate vibratory impressions to subjacent 

 nervous structures. (Fig. 5.) Their function 

 appears to be that of adjusting the balance of 

 the animal's swimming-bell in its passage 

 through the water. 



The ocelli consist of an arrangement of 

 sensory and pigment cells grouped into a 

 definite organ, in which some of the ocelli 

 project above the surface of the ectoderm in 



the form of a 

 cuticular lens. 

 (Fig. 6.) 



Ocelli are 

 sometimes al- 

 luded to as 



FIG. 6. " eye-spots/' in 



consequence of 



the part they play as receivers of the waves 

 of light which reach the animal from the 

 outer world. Mr. Romanes has proved that 

 Medusoids are influenced in their movements 

 by the stimulus of light; if the animal is 

 vigorous and swimming 'freely in water, the 

 effect of a momentary flash of light thrown 

 upon it during one of its natural pauses 



