To Mr. Darwin the author is indebted for the communication of some flowers of _Corydalis tuberosa_ (figs. 124, 125), provided with two spurs of nearly equal size. To these flowers allusion is made in the work already quoted[241] in the following terms:--"_Corydalis tuberosa_ properly has one of its two nectaries colourless, destitute of nectar, only half the size of the other, and therefore to a certain extent in a rudimentary state; the pistil is curved towards the perfect nectary, and the hood formed of the inner petals slips off the pistil and stamens in one direction alone, so that when a bee sucks the perfect nectary the stigma and stamens are exposed and rubbed against the insect's body. In several closely allied genera, as in _Dielytra_, there are two perfect nectaries; the pistil is straight, and the hood slips off on either side, according as the bee sucks either nectary." In the flowers of _Corydalis_, which were provided with two perfect nectaries containing nectar, Mr. Darwin considers that there has been a redevelopment of a partially aborted organ, accompanied by a change in the direction of the pistil, which becomes straight, while the hood formed by the petals slips off in either direction, "so that these flowers have acquired the perfect structure, so well adapted for insect agency, of _Dielytra_ and its allies." [Illustration: FIG. 124.--Two-spurred flowers of _Corydalis_.] [Illustration: FIG. 125.--Section through two-spurred flowers of _Corydalis_, Magnified.] Peloria, then, is especially interesting physiologically as well as morphologically; it is also of value in a systematic point of view, as showing how closely the deviations from the ordinary form of one plant represent the ordinary condition of another; thus, the peloric Calceolarias resemble the flowers of _Fabiana_, and De Candolle,[242] comparing the peloric flowers of _Scrophulariaceae_ with those of _Solanaceae_, concluded that the former natural order was only an habitual alteration from the type of the latter. Peloric flowers of _Papilionaceae_ in this way are indistinguishable from those of _Rosaceae_. In like manner we may trace an analogy between the normal one-spurred _Delphinium_ and the five-spurred columbine (_Aquilegia_), an analogy strengthened by such a case as that of the five-spurred flower of _Delphinium elatum_ described by Godron.[243] The _Corydalis_, before referred to, is another illustration of the same fact, the structure being the same as in _Dielytra_, &c.