s; antennae, nostrils turned outside in.

Duges also made a comparison of Articulates with Vertebrates.[139] He did
not accept Geoffroy's vertebral theory of the Arthropod skeleton, though
he admitted that in Arthropods the dorsal surface was turned towards the
ground, basing this assumption on the position of the nervous system,
and also, curiously enough, on the inverted position of the embryo on
the lower surface of the yolk. He considered that the mandibles and
first maxillae of Arthropods were the homologues of the upper and lower
jaws of Vertebrates, adducing as confirmatory evidence the fact that in
snakes the rami are separate. The labium was the equivalent of the
hyoid, the labial palps and maxillipedes the equivalent of the "hyoid"
elements which form the branchial arches.

But Duges' main contribution to morphological method was his conception
of the living organism as a colony of lesser units, which were
themselves real "organisms." "By _organism_ the author means a complex
of organs which taken together suffice to constitute, ideally or
actually, a complete animal. An 'organism' is, as it were, an elementary
or simple animal; several organisms combined form a complex animal" (p.
255). Duges hit upon this principle, which was first suggested to him by
A. Moquin-Tandon's work on the leech (1827), as a great aid in
demonstrating the unity of plan and composition throughout the animal
kingdom.[140] According to his view there are three main types of
animals--(1) Biserials, including bilaterally symmetrical animals,
composed of two parallel series of "organisms"; (2) Radiates, composed
of "organisms" arranged like the spokes of a wheel; and (3)
Raceme-animals, in which the separate "organisms" were disposed more or
less irregularly, in bunches (p. 257). The unitary "organism" is
supposed to be the same in all, only the arrangement differing. Duges of
course admitted that the centralisation of the complete organism became
greater the higher it stood in the scale, and that this held good also
in individual development. The appendages of Articulates and Vertebrates
were thought of as the members of as many separate organisms. He went so
far as to suggest that the fingers of a man's hand were the free
extremities of as many thoracic members.

Duges' conception of the organism has often been revived since in a
saner form, _e.g._, by E. Perrier, and it has a certain validity. It has
much affinity with the similar co