HYDRO IDS AND JELLY-FISHES. 47 



There are still other Jelly- Fishes and very beauti- 

 ful ones, having no connection with any Hydroid, and 

 simply reproducing themselves by eggs. 

 They may be found on our coasts, through- 

 out the spring and summer ; and I hope 

 you will have many a good ramble on the 

 rocks and beaches of Nahant to find 

 both Hydroids and Jelly-Fishes. 



There is one thing I must not forget to 

 tell you about the Jelly-Fishes before we 

 leave them. They are the lamps of the 

 sea. Have you ever heard of the phos- No . , 8> 

 phorescence of the ocean ? It is a strange 

 light on the surface of the water following in the wake 

 of vessels as they cut their way through the waves, or 

 seen at night along the line of foam that breaks upon the 

 shore. There are a variety of phosphorescent animals 

 in the sea, and a part of this singular illumination of the 

 ocean is due to all of them ; but the Jelly-Fishes are 

 among the brightest and most beautiful. The large ones 

 float slowly like translucent globes among the lesser lights, 

 while others sparkle like stars, or spread a more diffused 

 and paler light over the water. This luminous property 

 of the Jelly-Fishes belongs to their more active and sen- 

 sitive parts ; and the light is more perceptible when a 

 vessel breaks the surface of the sea, or where the waves 

 break upon the shore, because the disturbance of the 

 waters in which they float excites them into unusual 

 brilliancy. It is easy to watch the action of this sin- 

 gular quality in the Jelly-Fishes, by keeping them in 

 glass jars in a dark place. If you trouble the water 

 by passing your hand through it, they will begin to 



