Seeds of Hierarchy 183
fluids produce further advances in complexity unless changed environments elicit
altered habits, thus modifying form and permitting the ponderables to flow in new
ways (see Corsi, 1988, p. 200; and Burkhardt, 1977, p. 147).
PATTERN. The "pure" distinction of progress and adaptation should produce a
single linear chain (for progress) with lateral deflections (for adaptation). Lamarck
tried to construct such a topology, but could not carry his scheme to completion at
two important places—the top and bottom of the ladder—where environment
intruded upon the chain to blur the distinction of forces.
(1) Two sequences of spontaneous generation. Lamarck first proposed a
single linear series of animals, starting with the spontaneous generation of
infusorians (protistans) as free-living creatures in water. These unicells then
aggregated to polyps and their relatives, and then to simple, bilaterally symmetrical
worms (see Fig. 3-1). However, Lamarck later discovered worms (the acoelous
platyhelminths in modern terminology) without nerve cords. These worms ranked
"higher" than polyps on grounds of their mobility, but could not be the descendants
of polyps, unless the nerve cords of polyps had degenerated and disappeared—
impossibility under the "force that tends incessantly to complicate organization."
Thus, worms without nerve cords must represent part of a second and separate
sequence of progress. Lamarck proposed an origin for this second sequence in the
spontaneous generation of even simpler worms as parasites within the bodies of
other organisms. If dif-
3 - 1. Lamarck's linear series of animal organization, from volume 1 of the Philosophie zoologique
of 1809. (Author's collection.)