ZOOPHYTES 



353 



In fig. 871 a jelly-fish is represented in which the egg-cells 

 resemble Amcebse, and creep about in search of food on the 

 outer surface of the mouth-bearing tube which hangs down from 

 the umbrella of the parent. 



In Aurelia there are four plaited projections from the corners 

 of the mouth, in the folds of which part of the development takes 

 place. 



The life-histories of Sea- Flowers (Anthozoa), such as Sea- 

 Anemones and Corals, are less sensational in character than 



Fig. 871. A Jelly- Fish (Amal- 

 thcea amcebigera] , showing the 

 eggs creeping on the large mouth- 

 tube ; enlarged 



Fig. 872. Egg-cell of a coral (Corallimorphus rigidus], with cells 

 of the nutritive layer (above) projecting into it. Within the egg cell 

 are seen the large nucleus and numerous yolk -granules. Much en- 

 larged. 



those of the Ccelenterates already dealt with under this heading. 

 But they are not lacking in interesting features. In fig. 872 is 

 represented, on a greatly enlarged scale, the egg-cell of a sort 

 of coral, which develops in the proximity of the nutritive layer, 

 from which it is, in fact, derived. A little group of these cells 

 project into its substance, and serve as a means of supplying it 

 with food. 



In both Sea- Anemones and ordinary Corals it usually happens 

 that the early stages of development take place within the body 

 of the parent, as far as the free-swimming ciliated larval stage 

 {plamila). These larvae are then ejected through the mouth, later 

 on become fixed, and grow into adults. Their locomotor powers 

 prevent the fixed habit of the mature forms from becoming too 

 great a disadvantage to the species. 



