304 TlMEHRl. 
around the open end, is essentially a simple organism, 
though the buds produced during growth often remain 
attached for some time and indicate the colonial arrange- 
ment. The colony-forming Hydroids are essentially 
simple aggregates of such Hydra- like forms which have 
budded continuously to form little bushy growths, in 
which the separate buds bear a considerable resemblance 
to flowers on a plant. 
Among the sponges, the various buds or branches 
produced by the parent form sometimes remain 
distinctly noticeable ; but usually this condition is 
entirely lost, owing to extreme budding and the 
fusion of adjacent parts, coupled with the develop 
ment of a very large number of pores throughout the 
body substance, which more or less hide the primitive 
arrangement of parts and give the open or porous texture 
characteristic of the familiar washing sponge. 
Among the group of the Corals, the Sea-Anemones 
are simple forms ; but, in those that form colonies, the 
plant-like aspe6t is carried to an almost extreme 
point, as in the various kinds of Tree-corals, though 
many forms, instead of producing branching colonies, 
give rise to hemispherical or globular masses, which, 
owing to the close approximation of the little star-like 
animals composing them, resemble huge heads of flowers. 
These little star-like coral-forming beings, which, in the 
tree-like masses, generally stud the surface throughout 
and give the appearance of a mass of flowering axes, 
are in structure almost exa6tlv the same as the beautiful 
Sea-Anemones that are so abundant along the rocky 
shores of temperate climes ; but the Sea-Anemones, like 
the little fresh-water Polyp among the Hydroids, never 
