sulted some sagacious and experienced observers, and, after
deliberation, they concur in this view. In this respect, therefore, the
species of the larger genera resemble varieties, more than do the species
of the smaller genera. Or the case may be put in another way, and it may be
said, that in the larger genera, in which a number of varieties or
incipient species greater than the average are now manufacturing, many of
the species already manufactured still to a certain extent resemble
varieties, for they differ from each other by a less than usual amount of
difference.

Moreover, the species of the large genera are related to each other, in the
same manner as the varieties of any one species are related to each other.
No naturalist pretends that all the species of a genus are equally distinct
from each other; they may generally be divided into sub-genera, or
sections, or lesser groups. As Fries has well remarked, little groups of
species are generally clustered like satellites around certain other
species. And what are varieties but groups of forms, unequally related to
each other, and clustered round certain forms--that is, round their
parent-species? Undoubtedly there is one most important point of difference
between varieties and species; namely, that the amount of difference
between varieties, when compared with each other or with their
parent-species, is much less than that between the species of the same
genus. But when we come to discuss the principle, as I call it, of
Divergence of Character, {58} we shall see how this may be explained, and
how the lesser differences between varieties will tend to increase into the
greater differences between species.

There is one other point which seems to me worth notice. Varieties
generally have much restricted ranges: this statement is indeed scarcely
more than a truism, for if a variety were found to have a wider range than
that of its supposed parent-species, their denominations ought to be
reversed. But there is also reason to believe, that those species which are
very closely allied to other species, and in so far resemble varieties,
often have much restricted ranges. For instance, Mr. H. C. Watson has
marked for me in the well-sifted London Catalogue of plants (4th edition)
63 plants which are therein ranked as species, but which he considers as so
closely allied to other species as to be of doubtful value: these 63
reputed species range on an average over 6.9 of the