Final Causes and Contemponeous Physiology (translated from the Revue des duex Mondes) [pp. 291-321]

294 FINAL cAUSES. [April,
part exists between the arrangement of the organ and the purpose which it serves, ancient physiology thought that the
structure of an organ reveals its use, just as in human art,
the structure of a machine may show, ct priori, its design.
Anatomy was considered as the key to physiology; by means
of the scalpel the form and structure of the organs were made
manifest, and thence the use of the organs was deduced.
Sometimes these deductions led to remarkable discoveries. It
was in this manner that Harvey discovered the circulation of
the blood. At other times they led to error. Men frequently
believed that they deduced that which, in reality, they only
observed. We can understand what a considerable role the
principle of final causes played in this physiology.
If we are to believe the present masters of the science, this
method, which surbordinates physiology to anatomy, which
deduces uses and functions from the structure of organs, and
which is, therefore, more or less inspired with the principle of
final causes, has had its day; it has become unfruitful, and a
more philosophic and profound method must be substituted
for it. Nothing is more contrary to observation than to affirm
that the structure of an organ is an indication of its function.
However exactly the structure of the liver was known, it was
impossible to deduce from it the functions, or at least one of
the functions, namely, the secretion of sugar. The structure
of the nerves will never reveal to any one that these organs
are intended to transmit either movement or sensibility. Moreover, the same functions may be exercised by organs of the
most different structure. Respiration, for instance, is performed in one case by lungs, in another by the wind-pipe; indeed, in certain animals by the skin, and in plants by the leaves.
Reciprocally, the same organs in different animals may perform
very different functions; thus the natatory bladder of fishes,
which is the true analogue of the lungs of mammals, serves no
purpose, or almost none, for respiration, and is only an organ
of sustenance and equilibrium. Finally, in the lowest animals,
the organism is not distinguishable: one single homogeneous
and amorphous structure contains, virtually, the power of producing all the vital functions, digestion, respiration, reproduction, locomotion, etc.
From these considerations M. Claude Bernard concludes,