_The Functional Independence of the Elements or Units of the
Body._--Physiologists agree that the whole organism consists of a multitude
of elemental parts, which are to a great extent independent of each other.
Each organ, says Claude Bernard,[891] {369} has its proper life, its
autonomy; it can develop and reproduce itself independently of the
adjoining tissues. The great German authority, Virchow,[892] asserts still
more emphatically that each system, as the nervous or osseous system, or
the blood, consists of an "enormous mass of minute centres of action....
Every element has its own special action, and even though it derive its
stimulus to activity from other parts, yet alone effects the actual
performance of its duties.... Every single epithelial and muscular
fibre-cell leads a sort of parasitical existence in relation to the rest of
the body.... Every single bone-corpuscle really possesses conditions of
nutrition peculiar to itself." Each element, as Mr. Paget remarks, lives
its appointed time, and then dies, and, after being cast off or absorbed,
is replaced.[893] I presume that no physiologist doubts that, for instance,
each bone-corpuscle of the finger differs from the corresponding corpuscle
in the corresponding joint of the toe; and there can hardly be a doubt that
even those on the corresponding sides of the body differ, though almost
identical in nature. This near approach to identity is curiously shown in
many diseases in which the same exact points on the right and left sides of
the body are similarly affected; thus Mr. Paget[894] gives a drawing of a
diseased pelvis, in which the bone has grown into a most complicated
pattern, but "there is not one spot or line on one side which is not
represented, as exactly as it would be in a mirror, on the other."

Many facts support this view of the independent life of each minute element
of the body. Virchow insists that a single bone-corpuscle or a single cell
in the skin may become diseased. The spur of a cock, after being inserted
into the eye of an ox, lived for eight years, and acquired a weight of 306
grammes, or nearly fourteen ounces.[895] The tail of a pig has been grafted
into the middle of its back, and reacquired sensibility. Dr. Ollier[896]
inserted a piece of periosteum from the bone of a young dog under the skin
of a rabbit, and true bone was developed. A multitude of similar facts
could be given. The {370} frequent presence of hairs and of perfectly