Species

Species and the Birth of Modern Science 87

to Darwin’s later pangenesis hypothesis. As Eddy recounts the hypothesis, unused mol-
ecules in an organism are brought together and reassembled in the form of the organism
in the seminal uids. This notion of form being physical is in itself very Aristotelian,
as Sloan observes, but Buffon is also directly inuenced by Leibniz (which Sloan also
notes) and so there is a tension in his thought.^175 If species are forms, then forms must be
distinct, but if they are arbitrary, and grade into each other, as Leibniz taught the scala
naturae, then they are not distinct. Eddy discusses this and points out that Buffon did not,
in his view, propose at this stage a historical or biological conception of species so much
as a logical one,^176 but whether one adopts Sloan’s or Eddy’s view, he later came to adopt
both, and it is in this that he most inuenced his pupil Lamarck.
In the period of 1764–1765, Buffon moved to a temporal and physical conception,
beyond question. But he did not think that form changed; it was xed eternally, and at
best change could be a process he came to call degeneration in an essay in 1766 entitled
“De la dégénération des animaux.” Form could be modied, he thought, by external envi-
ronmental changes, but should the “species” be brought back into their ancestral environ-
ment, those changes would be reversed.^177 Such change from the premier souche was
primarily due to damage; Eddy says, “[f]ar from seeing degeneration in terms of organic
history, Buffon saw it as the death of the organic past; through degeneration, organisms
lose their organic identity, become weak and vitiated, and in extreme cases, have trouble
reproducing.”^178 Roger reports that Buffon carried out experiments on hybridization to
test this theory, and had surprising success, but that eventually he accepted that some
animals, particularly domesticated ones, do not revert to the purity of the wild type.
He did, however, allow that the natural unit of biology was not xed at a single
level. What the Linnaeans called genera were roughly more like the natural families
Buffon thought set the limits of variety. He noted in volume 6 of the Histoire (1779),
in the essay on sheep, that human intervention had caused many “species” of domes-
ticated animals to degenerate from a single stock:

These physical genera are, in reality, composed of all the species, which, by our man-

agement, have been so greatly variegated and changed; as have all those species, so

differently modied by the hand of man, have but one common origin in Nature, the

whole genus ought to constitute but a single species.^179

In his Histoire naturelle des oiseaux (1770), Buffon claims that the size of the

species of bird directly correlates with the number of species that degenerate from

the premier souche:

A sparrow or warbler has perhaps twenty times as many relatives as an ostrich or a tur-

key; for by the number of relatives I understand the number of related species that are

sufciently alike among themselves to be considered side branches of the same stem, or

at least ramications of stems that grow so closely together that one can suspect that they

(^175) Sloan 1985.
(^176) Eddy 1994, 648n.
(^177) Roger 1997.
(^178) Eddy 1994, 652.
(^179) “The Sheep,” Histoire Naturelle, Quadrupèdes, vol 33, tome 6, 121f quoted in Greene 1959, 147.