230 
LIFE, IN ITS INTERMEDIATE FORMS. 
mencing at a point far lower than that to which we have 
ascended in our previous observations, rises in uninter- 
rupted gradation, though not without many lateral rela- 
tions, to the very highest type of animal existence. 
If we have been in the habit of picking up sea-weeds 
from the shore where they have been washed by the 
waves, or from the little sheltered rock-pools where they 
delight to grow, we have often seen spread over their 
smooth fronds what looks like a little piece of muslin, 
only that it is more delicate, more filmy. It adheres 
quite firmly to the surface, so that it cannot be rubbed 
off ; and if we apply our thumb-nail to it, we discover 
that, thin as it is, tho substance of which its subtile 
meshes are composed is stony or shelly in its nature, and 
so hard as to scratch tho nail. What is it i It is one of 
the sea-mats (. Membrmipora pilosa). 
We bring the magnifying power of a pocket-lens, or a 
microscope, to bear on it, and our sense of beauty is at 
once gratified. We see a net- work of glassy cells, each 
closely resembling a slipper in shape, arranged in the most 
orderly manner side by side, yet so that the opening of 
one shall be in contact with the middlo of its nearest 
neighbour, sidewise, while the toe of the slipper touches 
the heel of the next, lengthwise. The margin of the orifice 
is a little thickened, like the binding of a slipper, and 
there are springing up from this rim six short spines 
which arch over the opening, and a very long one from 
the front which runs up in the lino of the instep. The 
slipper-like cell is transparent as glass, but in the sub- 
stance are seen many oval bladders or cavities. 
These cells are so many houses inhabited by active 
