306 
THE OCEAN WORLD. 
itself up by closing its valves, and the snail retires into its shell. This 
assemblage of small cells presented by the Bryozoaires has long been 
known as a polypier. “ We propose,” says our author, “ with very 
good reasons, to call it a Testier, or shell-builder.” 
This testier, in which each cell has its opening, is furnished with a 
naked cushion, dentate, spinous, or protected by an operculum or li<h 
and presents itself under every variety of form. It is sometimes an llS 
semblage of branching tubes, occasionally a rounded mass of spongy 
appearance, and now it presents itself as a flat lamelliform inarticulate 
expansion. In some of the marine species the shell of the mussel i s 
covered as with a fine lace. 
It is a remarkable fact that these cells are not always inert. The)’ 
seem to enjoy the power of motion. It is well known that the lea've® 
and branches of the sensitive plant ( Mimosa ) contracts and expan - 
under the touch of the linger ; the same phenomenon, according 
Mr. llymer Jones, takes place on touching the cells of certain sp eCieS 
of Bryozoaires. The moment they are touched they quickly inchn e 
themselves, and the movement is immediately communicated from °n e 
to the other, until all the colls of the community are in motion. 
Returning to the organization of the little creature which occupy, 
the cell, it is found that the upper and retractile portion, which is 0 
extreme delicacy, terminates anteriorly in a circle of long tentad e ®’ 
in the centre of which is the mouth. These tentacles are fring eCl 
laterally by a series of vibratile cilia. “ When the animal disph 1 ) 9 
itself,” says Bredol, “this circle of microscopic threads of estrenm 
tenuity first show themselves rising from the summit of the cell ; ^ llS 
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 appendag 69 
like very fine hairs, attached to them nearly at right angles, in addit 10 ^ 
!pt 
to the lateral cils already spoken of, which play a very important p al 
in the arrangements of most microscopic animals. At the mom& 
when the tentacles appear outside the cell, the tunic of the animal ctd e ’ 
unrolled. It soon spreads out its pretty little arms, the appendages a n 
which has the power of expanding or contracting itself, is 
— _ 1 1_ p 
cils beginning their rapid vibrations, until the eye, deceived by " 
rapidity and regularity of their movements, is dazzled, and the behol 
begins to think that he sees rosy drops of dew waving to and r °’ 
