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&c.), these are likewise the most abnormal in their teeth.
I know of no case better adapted to show the importance of the laws of variation and correlation, independently of utility and therefore of natural selection, than that before referred to, of the difference between the outer and inner flowers in some Compositous and Umbelliferous plants. Every one knows the difference in the ray and central florets of, for instance, the daisy, and this difference is often accompanied with the partial or complete abortion of the reproductive organs. But in some of these plants, the seeds also differ in shape and sculpture. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. These differences have been attributed by some authors to the pressure of the involucra on the florets, or to their mutual pressure, and the shape of the seeds in the ray-florets of some Compositæ countenances this idea; but with the Umbelliferæ, it is by no means, as Dr. Hooker informs me, the species with the densest heads which most frequently differ in their inner and outer flowers. It might have been thought that the development of the ray-petals by drawing nourishment from the reproductive organs had caused their abortion; but this can hardly be the sole cause, for in some Compositæ ... the seeds of the outer and inner florets differ without any difference in the corolla. Possibly these several differences may be connected with the different .. flow of nutriment towards the central and external flowers: we know, at least, that with normally irregular flowers, those nearest to the axis are most subject to peloria, that is they become symmetrical. I may add, as an instance of this, and of a striking case of correlation, that I have recently observed in many pelargoniums, that in the central flower of the truss, the two upper petals often lose their patches of darker colour; and