te blood corpuscles we have a very remarkable
resemblance to the amoeba; the contractile vacuole is absent, but we
have the protoplasmic body, the nucleus and nucleolus, and those
creeping fluctuations of shape through the thrusting out and
withdrawal of pseudopodia, which constitute "amoeboid" motion. They
also multiply, in the same way, by division.

Section 53. It is not only in the white corpuscle of the blood that we
find this resemblance; in all the firmer parts of the body we find, on
microscopic examination, similar little blebs of protoplasm, and at an
early stage of development the young rabbit is simply one mass of
these protoplasmic bodies. Their division and multiplication is an
essential condition, of growth. Through an unfortunate accident, these
protoplasmic blebs, which constitute the living basis of the animal
body, have come to be styled "cells," though the term "corpuscles" is
far more appropriate.

Section 54. The word is "cell" suggests something enclosed by firm
and definite walls, and it was first employed in vegetable histology.
Unlike the typical cells of animals, the cells of most plants are not
naked protoplasm, but protoplasm enclosed in a wall of substance
(cell wall) called cellulose. The presence of this cellulose cell wall,
and the consequent necessity of feeding entirely upon liquids and
gases that soak through it instead of being able to ingest a portion of
solid food is indeed, the primary distinction between the
vegetable and the animal kingdoms, as ordinarily considered.

Section 55. Throughout life, millions of these cells retain their
primary characters, and constitute the white corpuscles of blood,
"phagocytes," and connective tissue corpuscles; others again,
engage in the formation of material round themselves, and lie, in
such cases, as gristle and bone, embedded in the substance they
have formed; others again, undergo great changes in form and internal
structure, and become permanently modified into, for instance, nerve
fibres and muscle substance. The various substances arising in this
way through the activity of cells are called tissues, the building
materials of that complex thing, the animal body. Since such a
creature as the rabbit is formed through the co-operation of a vast
multitude of cells, it is called multicellular; the amoeba, on the other
hand, is unicellular. The rabbit may be thus regarded as a vast
community of amoeboid creatures and their products.