iginate from the type species by
"degeneration," then one might reasonably suppose that from a single
being Nature could in time produce all the other organised beings.[28]
Elsewhere, _e.g._, in the discourse _De la Degeneration des
Animaux_,[29] Buffon expresses himself with more caution. He finds that
it is possible to reduce the two hundred species of quadrupeds which
he has described to quite a small number of families "from which it is
not impossible that all the rest are derived."[30] Within each of the
families the species branch off from a parent or type species. This we
may note is a great advance on the linear arrangement implied in the
idea of an _Echelle des etres_.[31]

It is a mistake to suppose that Buffon was par excellence a maker of
hypotheses. On the contrary he saw things very sanely and with a very
open mind. He expressly mentions the great difficulties which one
encounters in supposing that one species may arise from another by
"degeneration." How does it happen that two individuals "degenerate"
just in the right direction and to the right stage so as to be capable
of breeding together? How is it that one does not find intermediate
links between species? One is reminded of the objections, not
altogether without validity, which were made to the Darwinian theory
in its early days. I cannot agree with those who think that Buffon was
an out-and-out evolutionist, who concealed his opinions for fear of
the Church. No doubt he did trim his sails--the palpably insincere
"Mais non, il est certain, par la revelation, que tous les animaux ont
egalement participe a la grace de la creation,"[32] following hard upon
the too bold hypothesis of the origin of all species from a single
one, is proof of it. But he was too sane and matter-of-fact a thinker
to go much beyond his facts, and his evolution doctrine remained
always tentative. One thing, however, he was sure of, that evolution
would give a rational foundation to the classification which, almost
in spite of himself, he recognised in Nature. If, and only if, the
species of one family originated from a single type species, could
families, be founded rationally, _avec raison_.

Buffon was, curiously enough, rather unwilling to recognise any
systematic unit higher than the species. Strictly; speaking there are
only individuals in Nature; but there are also groups of individuals
which resemble one another from generation to generation and are able
to breed toge