SPONGES AND ANIMALCULES 
367 
of flinty fibres that may be over a foot in height. 
One of the compound or social sea-anemones is in 
the habit of forming bark-like encrustations on this 
glassy stem, and it was for a long time doubtful whether 
the sea-anemone or the sponge produced the support- 
ing-stalk. 
The Animalcules, which represent the simplest 
and lowest forms of living animals, consist chiefly of 
organisms which are the equivalents of one of the 
single cells, or, as they might be termed, the 
“ life-bricks,” out of which all the higher animals, 
and also plants, are built up. They are of minute 
dimensions, and require the aid of the microscope 
for their proper investigation. Among the most 
highly organised members of this sub-kingdom 
mention must be made of the Ciliated Animalcules, 
or Infu- 
SORIA, 
socalled 
because 
they 
were 
first dis- 
covered 
inhabit- 
i n g de- 
caying 
V e S' e - 
PORTUGUESE BIRD'S-NEST SPONGE 
Dredged from a depth of 600 fathoms off the coast of 
Portugal, In Ife the hody^ or cup^"*' of this 
sponge ^as deep orange colour^ from 'which 
the grey beard-like mass of anchoring 
fibres depended 
Photo by E, Connold'] [' 5 ^. Leonards 
CHALINA SPONGE 
Composed partly of horny and partly of flinty elements 
table 
and ani- 
mal i n- 
f u s i o n s. 
The so- 
called 
Slipper- ANIMALCULE is one of the commonest 
forms which makes its appearance amidst such 
environments. The length of this single-celled 
animal scarcely averages the one-hundredth part 
of an inch, but within this restricted space an 
amazing degree of structural and functional 
differentiation is included. Its outer surface 
is, in the first place, densely clothed with hairs, 
which represent its organs of locomotion. This 
outer cell-wall has a subjacent somewhat softer 
layer, in which are developed as crowded a series 
(as compared with the hairs) of minute rod-like 
bodies, which, under various stimuli, can be shot 
out like darts through the skin, and are adjudged 
to be offensive and defensive weapons, partaking 
much of the same nature as the thread- or 
stinging-cells of sea-anemones. Among other 
noteworthy structures, the slipper-animalcule 
