THE BRYOZOA. 17/23 
one of the zoophytes be touched, it instantly inclines to its neigh- 
bour, communicates the alarm, and withdraws into its cell, and, 
in an incredibly short time, the whole population of the colony is 
safely housed; however, confidence is soon restored, one by one 
they come out of their cells, and once more the daily life of the 
community is in full operation. 
Ehrenberg and Thompson, who have carefully studied these 
animal mosses, find a considerable difference between them and 
the polypidoms of the anthozoa. The cell of the coral is a 
solid fixture, and after the polype has built its house, it has no 
further control over it; but this is not the case with the cell of 
the bryozoa and its occupant—the creature can turn its cell inside 
out, like the finger of a glove; and by this means the zoophyte can 
AN OPEN LAGUNCULA. 
actually go out of its cell, although it cannot leave the settlement. 
When the animal displays itself, a circle of microscopic threads, 
of extreme tenuity, first show themselves above the edge of the 
cell; the uppermost portion of the body of the zoophyte next 
appears; then come the tentacles, which push the hairs aside. 
These tentacles have upon their surface a number of short hairs 
standing out at right angles, and they also are furnished with 
those peculiar organs—so universally distributed throughout the 
tribes of animalcules—vibratory cils. After the tentacles are 
spread, the tunic of the zoophyte unrolls itself, and the creature 
has reached the length of its tether, and is fully expanded. The 
action of its life commences; the appendages and the cils begin 
their rapid vibrations, by which currents are produced in the water 
—currents which bring within their reach the food necessary for 
the weal of the colony. Over the whole surface of the polyzoary 
eddy thousands of whirlpools, more fatal to the infusores which pass 
