iroW JELLT-FISH GROW. 



25 



ous branches, which connect with the marginal vessel 

 The Aurelia spawns late in the summer. 



The eggs pass out of tlie mouth into the water along the 

 channelled arms, and in October the ciliated sac orgastrnla 

 becomes pear-shaped and attaches itself to rocks, dead 

 shells, or sea-weeds, and then assumes a Hydra form xvith 

 often twenty-four very long tentacles. This stagf> was 



Fig. 23. — Sertularia abietinaoi-T^nro^Q. ^.natural size; i?, magnified, show 

 in^ ttie cells containing the animais. 



originally described as a distinct animal under the name ol 

 Scypliistoma. In this Scyphistoma stage (Pig 24) it re- 

 mains about eighteen months. Toward the end of this 

 period the body increases in size and divides into a series of 

 cup-shaped disks. These saucer-like disks are scalloped on 

 the upturned edge, tentacles bud out, and the animal as- 

 sumes the Strobila stage (Fig. 25). Finally, the disks sep- 

 arate, the upper one becomes detached and dies, but the 



