es Poissons_ (1828), he
insists on the necessity of excluding function from consideration in any
truly philosophical treatment of comparative anatomy (Discours prel., p.
25). Cuvier held that function determined structure, or at least that
the necessity of adaptation ruled the transformations of form. Geoffroy
considered that structure determined function, that changes of
structure, however they might arise, caused changes of function.
"Animals," he writes, "have no habits but those that result from the
structure of their organs; if the latter varies, there vary in the same
manner all their springs of action, all their faculties and all their
actions."[121]

Again, "a vegetarian regime is imposed upon the Quadrumana by their
possession of a somewhat ample stomach, and intestines of moderate
length."[122] The hand of the bat has become so modified as to constrain
the bat to live in the air.[123]

The best example of Geoffroy's insistence upon the priority of structure
to function, and so of his purely morphological attitude, is perhaps his
interpretation, already alluded to, of the appendages of Articulates.
The segments of the Articulate are, he says, the equivalents of the
bodies of the vertebrae of higher forms. Now "from the circumstance that
the vertebra is external, it results that the ribs must be so too; and,
as it is impossible that organs of such a size can remain passive and
absolutely functionless, these great arms, hanging there continually at
the disposition of the animal, are pressed into the service of
progression, and become its efficient instruments."[124] The ribs become
locomotory appendages.

We may compare the similar thought that the ear ossicles are simply
opercular bones reduced and turned to other uses.

Geoffroy could not but recognise the correlation of structure to
function, for this is a fact which imposes itself upon every observer.
He recognised also correlation between functions, as when he pointed out
the connection between increased respiration and enhanced muscular
activity in birds.[125] He interpreted structure at times in terms of
function, the short, strong clavicle of the mole as an adaptation to
digging, the keeled sternum of birds as an adaptation to flying, and so
on. But we may say that his whole tendency was to disregard function, to
look upon it as subsidiary. He protests against arguing from function
and habits to structure, as an "abuse of final causes."[126] He was no