o meet new requirements, that she is
not limited, as Geoffroy thought, to a definite number of "materials of
organisation," but can produce others at need. Cuvier held, for example,
that many of the muscles and even the bones of fish were peculiar to
them, and without homologues in the other Vertebrates, having been
created by Nature for special ends.[308] So, too, Johannes Mueller, who in
many ways and not least in his sane vitalism was a follower of the
Cuvierian tradition, recognised that many of the complicated cartilages
in the skull of Cyclostomes were specially formed for the important
function of sucking, and had no equivalent in other fish.[309]

So, too, the embryologists after Cuvier often came across instances of
the special formation of parts to meet temporary needs. Thus Reichert
interpreted the "palatine" and "pterygoid," which are formed in the
mouth of the newt larva by a fusion of conical teeth, as special
adaptations to enable the little larva to lead a carnivorous life.[310]

Not many years after the publication of Milne-Edwards' _Introduction a
la zoologie generale_ (1851) there appeared a book by H. G. Bronn in
which was offered a very similar analysis of organic diversity. The
curious thing was that Bronn approached the problem from quite a
different standpoint, from the standpoint, indeed, of
_Naturphilosophie_. Of this the title of the book is itself sufficient
proof--_Morphologische Studien ueber die Gestaltungs-gesetze der
Naturkoerper ueberhaupt und der organischen insbesondere_ (Leipzig and
Heidelberg, 1858).[311] The linking up of organic with inorganic form is
characteristic; there is much talk, too, in the book of _Urstoffe_ and
_Urkraefte_, but underlying the _Naturphilosophie_ we can trace the same
Cuvierian treatment of form, and see crystallise out laws of progressive
development that bear no small analogy with the laws established by
Milne-Edwards.

According to Bronn, the ideal fundamental form of the plant is an ovoid
or strobiloid[312] body, for a plant reaches out in two directions in
search of food--towards the sun and towards the earth. Animals differ
from plants in being endowed with sensation and mobility (_cf._
Aristotle and Cuvier), and it is this characteristic that gives them
their distinctive form. The main types of animal form--the Amorphozoa,
Actinozoa, and Hemisphenozoa--are essentially adaptations to particular
modes of locomotion. Animals either are fixed, or they