ation between blue eyes and deafness in cats, and the tortoise-shell
colour with the female sex; the feathered feet and skin between the outer
toes in pigeons, and the presence of more or less down on the young birds
when first hatched, with the future colour of their plumage; or, again, the
relation between the hair and teeth in the naked Turkish dog, though here
probably homology comes into play? With respect to this latter case of
correlation, I think it can hardly be accidental, that if we pick out the
two orders of mammalia which are most abnormal in their dermal covering,
viz. Cetacea (whales) and Edentata (armadilloes, scaly anteaters, &c.),
that these are likewise the most abnormal in their teeth.

I know of no case better adapted to show the importance of the laws of
correlation in modifying important structures, independently of utility
and, therefore, of natural selection, than that of the difference between
the outer and inner flowers in some Compositous and Umbelliferous plants.
Every one knows the {145} difference in the ray and central florets of, for
instance, the daisy, and this difference is often accompanied with the
abortion of parts of the flower. But, in some Compositous plants, the seeds
also differ in shape and sculpture; and even the ovary itself, with its
accessory parts, differs, as has been described by Cassini. These
differences have been attributed by some authors to pressure, and the shape
of the seeds in the ray-florets in some Compositae countenances this idea;
but, in the case of the corolla of the Umbelliferae, it is by no means, as
Dr. Hooker informs me, in species with the densest heads that the inner and
outer flowers most frequently differ. It might have been thought that the
development of the ray-petals by drawing nourishment from certain other
parts of the flower had caused their abortion; but in some Compositae there
is a difference in the seeds of the outer and inner florets without any
difference in the corolla. Possibly, these several differences may be
connected with some difference in the flow of nutriment towards the central
and external flowers: we know, at least, that in irregular flowers, those
nearest to the axis are oftenest subject to peloria, and become regular. I
may add, as an instance of this, and of a striking case of correlation,
that I have recently observed in some garden pelargoniums, that the central
flower of the truss often loses the patches of darker colou