known in which the progeny of B, by sexual generation, is other than a
reproduction of A.

But if this be a true statement of the nature of the process of
Agamogenesis, how can it enable us to comprehend the production of new
species from already existing ones? Let us suppose Hyaenas to have
preceded Dogs, and to have produced the latter in this way. Then the
Hyena will represent A, and the Dog, B. The first difficulty that
presents itself is that the Hyena must be asexual, or the process will
be wholly without analogy in the world of Agamogenesis. But passing
over this difficulty, and supposing a male and female Dog to be
produced at the same time from the Hyaena stock, the progeny of the
pair, if the analogy of the simpler kinds of Agamogenesis* is to be
followed, should be a litter, not of puppies, but of young Hyenas. For
the Agamogenetic series is always, as we have seen, A: B: A: B, etc.;
whereas, for the production of a new species, the series must be A: B:
B: B, etc. The production of new species, or genera, is the extreme
permanent divergence from the primitive stock. All known Agamogenetic
processes, on the other hand, end in a complete return to the
primitive stock. How then is the production of new species to be
rendered intelligible by the analogy of Agamogenesis?

[footnote] * If, on the contrary, we follow the analogy of
the more complex forms of Agamogenesis, such as that
exhibited by some 'Trematoda' and by the 'Aphides', the
Hyaena must produce, asexually, a brood of asexual Dogs,
from which other sexless Dogs must proceed. At the end of a
certain number of terms of the series, the Dogs would
acquire sexes and generate young; but these young would be,
not Dogs, but Hyaenas. In fact, we have 'demonstrated', in