Many instances could
be given to prove that progression and retrogression are the two main
principles of evolution at large. Hence the conclusion, that our
analysis must dissect the complicated phenomena of evolution so far as
to show the separate functions of these two contrasting principles.
Hundreds of steps were needed to evolve the family of the orchids, but
the experimenter must take the single steps for the object of his
inquiry. He finds that some are progressive and others retrogressive and
so his investigation falls under two heads, the origin of progressive
characters, and the subsequent loss of the same. Progressive steps are
the marks of elementary species, while retrograde varieties are
distinguished by apparent losses. They have equal claim to our interest
and our study.
As already stated I propose to deal first with the elementary species
and afterwards with the retrograde varieties. I shall try to depict them
to you in the first place as they are seen in [16] nature and in
culture, leaving the question of their origin to a subsequent
experimental treatment.
The question of the experimental origin of new species and varieties has
to be taken up from two widely separated starting points. This may be
inferred from what we have already seen concerning the two opposing
theories, derived and isolated from Darwin's original broad conception.
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