THE .SPONGES. wal 
They grow, erect or pendant, according to the body which supports 
them and their natural habit. This fixed position of certain 
animals is a very peculiar character. Most people imagine that 
animals have the power of moving from one place to another; but 
this is not always the case; there are numerous species which live 
and die attached to the same place, such as polypes and sponges. 
The adherence of animals to a fixed position causes them to be 
more under the influence of external agents than others which 
are endowed with locomotion; these can frequently escape those 
changes, which would otherwise affect them, by moving from that 
particular position, or sometimes by periodical migrations. Hence 
there is the greatest difference in the habits and powers of fixed and 
moving animals. 
Three hundred species of sponges are known. They are 
classed as Pedicellated, Non-pedicellated, Foliaceous, Globular, 
Concave, and Digitated. Their various forms account for the 
singular names given them by sailors; for instance, the /eather 
Sponge, the Fan, the Bell, the Lyre, the Trumpet, the Drstaff, the 
Peacock's Tawl, and Neptune's Glove. 
Nature has been as careful in the construction of the humblest 
inhabitants of the water, as of those beings which belong to the 
higher orders of creation. The touches of the great Master’s hand 
are always perfect. 
The common sponge is an irregular round mass, often a little 
concave. On examining its tissue with a lens, we find it is 
composed of fine, flexible fibres, interlacing each other, and form- 
ing a vast number of orifices, some of which are very small (ores), 
and are found spreading over the whole surface of the sponge, 
while some much larger (oscu/es), are generally situated on the upper 
surface. In the interior, irregular canals of all dimensions lead into 
each other, and make a communication with the pores and the 
orifices. The tissue is, as it were, stuffed with hard bodies called 
spicule, calcareous or siliceous. Some are straight, like needles; 
others are divided into two or three branches. In the living 
state this mass is surrounded by a layer of mucous matter, 
which becomes sticky when the polype is taken from the water. 
Strong currents are found to pour forth from each orifice, living 
