world. While the first comprises only
microorganisms which have remained in the rudimentary state, animals and
vegetables have taken their flight toward very lofty fortunes. Such,
indeed, is generally the case when a tendency divides. Among the
divergent developments to which it gives rise, some go on indefinitely,
others come more or less quickly to the end of their tether. These
latter do not issue directly from the primitive tendency, but from one
of the elements into which it has divided; they are residual
developments made and left behind on the way by some truly elementary
tendency which continues to evolve. Now, these truly elementary
tendencies, we think, bear a mark by which they may be recognized.

This mark is like a trace, still visible in each, of what was in the
original tendency of which they represent the elementary directions. The
elements of a tendency are not like objects set beside each other in
space and mutually exclusive, but rather like psychic states, each of
which, although it be itself to begin with, yet partakes of others, and
so virtually includes in itself the whole personality to which it
belongs. There is no real manifestation of life, we said, that does not
show us, in a rudimentary or latent state, the characters of other
manifestations. Conversely, when we meet, on one line of evolution, a
recollection, so to speak, of what is developed along other lines, we
must conclude that we have before us dissociated elements of one and the
same original tendency. In this sense, vegetables and animals represent
the two great divergent developments of life. Though the plant is
distinguished from the animal by fixity and insensibility, movement and
consciousness sleep in it as recollections which may waken. But, beside
these normally sleeping recollections, there are others awake and
active, just those, namely, whose activity does not obstruct the
development of the elementary tendency itself. We may then formulate
this law: _When a tendency splits up in the course of its development,
each of the special tendencies which thus arise tries to preserve and
develop everything in the primitive tendency that is not incompatible
with the work for which it is specialized._ This explains precisely the
fact we dwelt on in the preceding chapter, viz., the formation of
identical complex mechanisms on independent lines of evolution. Certain
deep-seated analogies between the animal and the vegetable have probabl