36 LIFE AND HER CHILDREN. 
The floor on which they grow is often as beautiful 
as they are themselves, with its covering of tangled 
seaweeds, among which live the many shelled 
creatures of the sea, while fish swim hither and 
thither, and the whole region is teeming with life 
"Of sea-bom kinds, ten thousand thousand tribes, 
Find endless range for pasture and for sport." 
Such is the Sponge-kingdom, and the whole colony 
of sponges of every shape and size flourish like 
monarchs in their domain. So long as they are 
alive few can attack them and fewer conquer or 
destroy them. Only the sponge-fisher diving down 
into the rich colony disturbs its peace, and tearing 
the living sponge ruthlessly from its rocky bed, 
wrings out the living slime, and destroys the animal 
for the sake of its skeleton. 
Every three years this destroyer visits the 
sponge-colony, for he knows that in spite of his having 
carried off all the best and richest specimens, this 
interval is enough for new sponge-animals to have 
grown up so as to weave large and perfect skeletons. 
What secret then has Life taught to the sponge- 
animal, that while it is still only slime it can grow 
into such large masses and protect itself so well against 
the other inhabitants of the sea ? We will answer 
this question by tracing the growth of a sponge from 
its birth, and reading its history. 
If you wish to watch a living sponge yourself, 
you have only to keep one in a salt-water aquarium, 
for small sponges are easily found alive on our 
English coast, though they will not look like those 
we use. In this description, however, we will ima- 
