HOW SPONGES LIVE. 
37 
gine that we can visit one of the sponge -colonies 
in the Mediterranean Sea 
or the Gulf of Mexico, Fl >- ro - 
where the rocks from fifty _ ; ~^._ 
to a hundred and fifty feet _~ ^IJ^l"^ 
below the surface of the =^^^.g ^^ 
clear blue water are covered p^: ==$ 
with sponges of every size, ~ 
and shape, and texture. 
If we could visit these 
sponge - beds during the iJJ| 
summer or autumn months, 
and examine carefully the 
slimy lining of one of the 
bigf tubes of a 
&%& 
^Spe= 
rS&jrJ^S 
livin 
sponge, we should find that fl 
minute ba^s of slime 
*- ~"~ - 
--==_- 5--_i^;-3 
(i, a, Fig. 11) are begin- =gj ) 
ning to appear in it, either s 
scattered 
through 
sponge or collected in heaps. 
These are spon^e-ec^s, out 
X O O O - A rt * i r i 
r u" u A British sponge found at 
Of Which young sponges Brighton-life-size. 
are to grow, and in many 
ways they are very like a hen's egg. Within, 
as may be seen through their transparent cover- 
ing, is something which answers to the yelk of 
an egg, with a solid spot or nucleus in it. This 
yelk begins soon to divide into two cells, or separate 
masses of slime, and these ag^in divide into four, 
these four into eight, and so on till the egg is a 
globe of small round cells, the beginning of the 
young sponge. And now a change may be seen to 
4 
