Species

74 Species

In the Historia plantarum generalis, in the volume published in 1686, Ray dened
a species thus:

So that the number of plants can be gone into and the division of these same plants

set out, we must look for some signs or indications of their specic distinction (as they

call it). But although I have searched long and hard nothing more denite occurs than

distinct propagation from seed. Therefore whatever differences arise from a seed of a

particular kind of plant either in an individual or in a species, they are accidental and

not specic. For they do not propagate their species again from seed; thus, for example,

we do not have Caryophylli with a full or multiple ower distinct in species from

Caryophylli with a simple ower, because they derive their origin from their seed, and

when sown from seed produce simple Caryophylli again. But those which never arise

with the same appearance from seed, are indeed to be considered specic; or if com-

parison is made between two kinds of plant, those plants which do not arise from the

seed of one or the other, nor when sown from seed are ever changed one into the other,

these nally are distinct in species.

For thus in animals a distinction of sexes does not sufce for proving a diversity

of species, because both sexes arise from the same kind of seed and frequently from

the same parents, although by many striking accidents they differ among themselves.

It requires no other proof that a bull is of the same species as a cow, and a man as a

woman, than that both have very often arisen from the same parents or from the same

mother. So, equally in plants, there is no more certain indication of a sameness of spe-

cies than to be born from the seed of the same plant either specically or individually.

For those which differ in species keep their own species for ever, and one does not arise

from the seed of the other and vice versa.^119

Mayr notes, “Here was a splendid compromise between the practical experi-
ence of the naturalist, who can observe in nature what belongs to a species, and the
essentialist denition, which demands an underlying shared essence.”^120 However,
it seems to me the inuence of the generative conception is more apparent here.
Ray is dealing with the Aristotelian problem of accidental variation—like Locke
he believes there must be a real essence, and not merely a nominal one. He con-
jectures that the real essence is, or rather denes it to be, based upon descent by
generation. But in most cases, as many have observed since (see below, Buffon),
descent is not observable; and he clearly did not observe the fact that one species
never springs from the seed of another. In fact, he wrote, in the Methodus plantarum
of 1682:

... I would not have my readers expect something perfect or complete; something

which would divide all plants so exactly as to include in positions anomalous or pecu-

liar; something which would so dene each genus by its own characteristics that no

species be left, so to speak, homeless or be found common to many genera. Nature

does not permit anything of the sort. Nature, as the saying goes, makes no jumps and

passes from extreme to extreme only through a mean. She always produces species

(^119) Lazenby 1995, 1157, Vol. III, chapter 20.
(^120) Mayr 1982, 257.