54 



Chapter III 



of this extremity is an elongated opening, the mouth, which 

 leads into a spacious sac, often spoken of as the stomach. It is, 

 however, only a kind of oesophagus, through which the food passes 

 into the large coelenteric cavity which is divided by septa into 

 numerous compartments lined by the entodermic epithelium. These 

 septa give origin to many very long and tortuous filaments, spoken of 

 as mesenterial filaments from their resemblance, a purely superficial 

 one, to the mesentery of higher animals (fig. 10). When the Actinian 

 is hungry it protrudes its tentacles in order to seize marine animals, 

 which it conducts to its mouth. The lips and the oesophagus are 

 [58] used to estimate the quality of the capture, and if it is found 

 unsuitable the anemone rejects it, first surrounding it with a layer of 



FIG. 10. Longitudinal section of 

 an Actinian (after Hollard). 



FIG. 11. An Actinian in which carmine 

 after absorption has passed into the 

 mesenterial filaments. 



mucus. If however the food is found to be suitable, the Actinian 

 retains it in its large cavity and throws around it a multitude of its 

 mesenterial filaments. These penetrate it in all directions, and as 

 their epithelial cells are capable of sending out amoeboid processes 

 they seize and ingest the particles, which immediately enter the proto- 

 plasmic content. This work is done with such precision and nicety 

 that the sea-anemone is able to extract the contents of a shrimp from 

 the carapace, which latter alone it rejects. 



