304 THE OCEAN WORLD. 



known as a coral. " We propose," says our author, " with very good 

 reasons, to call it a Testier, or shell-builder." 



This testier, in which each shell has its opening, is furnished with a 

 naked cushion, dentate, spinous, or protected by an operculum or lid, 

 and presents itself under every variety of form. It is sometimes an as- 

 semblage of branching tubes, occasionally a rounded mass of spongy 

 appearance, and now it presents itself as a flat lamelliform inarticulated 

 expansion. In some of the marine species the shell of the mussel is 

 covered as with a fine lace. 



It is a remarkable fact that these cells are not always inert. They 

 seem to enjoy the power of motion. It is well known that the leaves 

 and branches of the sensitive plant (Mimosa) contract and expand 

 under the touch of the finger ; the same phenomenon, according to 

 Mr. Kymer Jones, takes place on touching the cells of certain species 

 of Bryozoaires. The moment they are touched they quickly incline 

 themselves ; and the movement is immediately communicated from one 

 to the other, until all the cells of the community are in motion. 



Eeturning to the organization of the little creature which occupies 

 the cell, it is found that the upper and retractile portion, which is of 

 extreme delicacy, terminates anteriorly in a circle of long tentacles, 

 in the centre of which is the mouth. These tentacles are fringed 

 laterally by a series of vibratile cilia. " When the animal displays 

 itself," says Fredol, " this circle of microscopic threads of extreme 

 tenuity first show themselves rising from the summit of the cell ; this 

 is followed by the upper part of its body, which is more or less flexible ; 

 the tentacles follow between the threads, pushing them on one side." 



These tentacles are furnished on the back with a dozen appendages 

 like very fine hairs, attached to them nearly at right angles, in addition 

 to the lateral cilia already spoken of, which play a very important part 

 in the arrangements of most microscopic animals. At the moment 

 when the tentacles appear outside the cell, the tunic of the animalcule, 

 which has the power of expanding or contracting itself, is gradually 

 unrolled. It soon spreads out its pretty little arms, the appendages and 

 cilia beginning their rapid vibrations, until the eye, deceived by the 

 rapidity and regularity of their movements, is dazzled, and the beholder 

 begins to think that he sees rosy drops of dew waving to and fro, 

 twisting and untwisting themselves. The corpuscles which float round 

 the animal are violently agitated, as if they were under the influence of 



