THE GROWTH OF JELLY-FISHES. 581 



nervous system, which again is brought into relation with the ex- 

 ternal world by means of special sense-organs. It is a gelatinous 

 bell, from the inner surface of which the pendent stomach hangs 

 down like the bell-clapper, while the long, graceful, thread-like 

 tentacles are attached at regular intervals around the opening of 



¥iQ. a.—Liriope sciitigera, slightly magnified, drawn from Nature by W. K. Brooks. (The BmaU 

 fifmre in the left-hand lower corner is the planula of Turritopsis, greatly magnified ; and the 

 one in the right-hand comer, the root and the first hud of the Turritopsis hydroid.) 



the bell. The locomotor muscles are so distributed over the inner 

 surface of the bell that their contraction squirts out the water in 

 a jet which propels the animal in the opposite direction ; they are 

 then relaxed, and the elasticity of the gelatinous substance of the 

 wall of the bell causes it to expand and to draw in another supply 



