430 NATURAL CARVINGS. 
ilating nourishment, and of exerting movements. Nay, 
more, it can produce a shell; a structure, in many cases, 
of extraordinary complexity and most singular beauty.” 
With the Rhizopoda, however, we have not to do at present ; 
at some future time we shall take the opportunity of pre- 
senting our readers with some figures illustrating the grace 
exhibited in some of their hard tissues, or skeletons, as we 
may rightly term them. 
Our Polycistinez belong to a class of animals very nearly 
allied to those we have just been speaking of, and named by 
naturalists Radiolaria. This name has been given to them 
on account of the radiating arrangement of their parts, 
such parts being grouped, generally, around a common cen- 
tre. These simple forms of life consist of microscopic 
masses of the semigelatinous substance we have already 
spoken of, and which is known as sarcode, meaning matter, 
as it were, on the way to become flesh, or protoplasm, from 
words designating the first form of matter. This term, how- 
ever, is more commonly applied to the primitive tissue of 
the embryo or egg, out of which all subsequent organs are 
formed by a peculiar process, termed differentiation. From 
this mass of sarcode, constituting the whole mass of the 
animal proper of the Radiolarian organism, are protruded 
filaments, which are often extremely long and slender, and 
have been named pseudopodia, from two words meaning 
false feet; for these projections act as feet to the creature 
which throws them out, serving not only as organs of propul- 
sion but to secure its prey and convey its food into the posi- 
tion for assimilation, and the building up of new tissues. 
This sarcode is such a peculiar kind of substance that the 
pseudopodia, as they are thrown out, may remain single or 
unite so as to form reticulations, or even coalesce into one 
mass around any particle of nutrient matter which they come 
in contact with. Scattered throughout it, generally, are 
to be found numerous yellow corpuscles, which multiply by 
fission, as it is called, or division, and to these parts a skele- 

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