the
permanent structure of the lower animals. Indeed, some of the lower
forms of animal life are simply cells. How vast the difference between
the organism of man, with all its complexity of structure, and that of
the Ameba or Actinophrys, which, being merely a homogeneous mass of
organic matter, performs all the functions of its simple life without
any special organ whatever! Yet, is man any less a unit than the Ameba,
or any other simple organism? Does his multiplicity of organs impair the
integrity of his anatomical and physiological oneness? Is the
circulation independent of respiration? Is digestion independent of the
circulation? Can any one organ act independently of the others? Is not
the entire series of parts, organs, and functions bound up in complete
and inseparable unity? The vicarious action of one organ for another has
been a question among physiologists; and if admitted, as in the case of
the salivary glands acting for the kidneys in profuse spitting, and the
skin for the liver, the vicarious function can only obtain to a slight
degree and in a temporary manner. The destruction of any considerable
organ involves the destruction of all the rest. I repeat that the
integrity of the physiological unity at the top of the scale, is far
more complete, with all its complexity, than is the integrity of the
physiological unity at the bottom of the scale, with its marked
simplicity of structure. By no sort of legerdemain or surgical skill can
we make an individual mammal become two. If we divide it, the whole
dies. Not so, however, with some of the lower grades of animal
existence. Cut a hydra into thirty or forty pieces, and each piece will
become a distinct animal--a facsimile of the original one. In quite an
analogous way do a large number of animals at the lower end of the scale
propagate, by segmentation and division; one individual becoming two,
two four, and so on.

Many examples might be adduced to show the absence of organized unity in
the lower orders of the animal creation. Thus, in the annelid, which is
composed of a great many similar rings, and is regarded as quite a
complex creature, there is so little dependence of one part on another,
that a number of the rings may be destroyed without any injury to the
rest. The Synapta, when in want of food, will amputate its own body to
procure the necessary supply; and it has been observed to repeat the
operation, until it 'had by degrees eaten away the whole o