382 HISTORY OF BRITISH ZOOPHYTES. 
be ascertained even with the naked eye. By the aid of a 
lens, however, the nature of the change is much more evi- 
dent. You then see that the branches are tubes, inhabited 
by living creatures ;—that long bud is a cell, the dwelling- 
place of a polype; that there may be above a hundred of 
these clustered together; and that as one stone may have 
several distinct v2Z/ages planted upon it, the whole popula- 
tion of a district of six square inches may be upwards of a 
thousand. The first symptoms of life that the observer 
perceives is the polype, which had shrunk out of sight on 
being disturbed, pushing forward to the mouth of the cell, 
as if to reconnoitre. If all is quiet, you will soon see the 
polype, in the form of a little white rod, protrude from 
the cell in a horizontal direction. This rod is composed of 
a bundle of tentacula, amounting to about fifty. The next 
change that takes place is the unfolding of the tentacula ; 
not,in the star-lke form assumed by the Hydra, but in the 
form of two horse-shoes, the one enclosing the other. The 
outer and larger horse-shoe is spread out like a lady’s ivory 
fan. ‘The inner range is unfolded in the same manner, but 
it is of smaller dimensions. There is something remarkably 
elegant in this form of the polype; and though it is the 
more usual aspect, it is not the only one. There is another 
