The second objection of the illustrious British botanist is of no greater weight. What we, with so many others, call an ovule, appeared to him not sufficiently complicated in structure to be considered as such. But we are all aware that the ovule is not necessarily composed of a nucleus and its two envelopes. Brongniart, Decaisne, and R. Brown himself, have long ago described plants in which the ovule is reduced to its nucleus alone. Botanists have too often confounded in the Abietineæ the scales of an appendicular [foliar] nature, which are borne by the axis of the cone, with the organs situated in the axils of these leaves, to which, from their appearance, the same name has been applied. But henceforth this confusion should be so much the more easily prevented, since Phytotomists are every day attaching less importance to the consistence, form, and colour of an organ, when determining its signification. That which bears the female reproductive organs in the Abietineæ is a body placed in the axil of a leaf (appendice); it is then a branch—an axial production—and in relation to this Schleiden has opened the way to an exact determination of the nature of the floral supports. It is incontestable that the axiom "folium in axillâ folii is without example in the vegetable kingdom," holds true in this, as in every other case. We should not then be arrested by the objection which Dr Lindley addresses to Schleiden. (Veget. Kingd. 2d edit. p. 227.) It is begging the question to consider the fruit of a Willow as "a leaf placed in the axil of another leaf." For even admitting that the placentas of a Willow are formed by the borders of the carpellary leaves, nevertheless there are here two leaves united so as to form the ovary, and they represent a bud with two leaves, to which a receptacle or common support is certainly necessary of an axial nature, let it be as short as one chooses. The comparison which some would establish between the flowers of the two sexes proves nothing in favour of the foliar nature of the body supporting the seeds in the Abietineæ; for the stamens are not, as Dr Lindley plainly says, "the analogues of he indurated carpellary scales of the females." These supposed carpels are, in fact, placed in the axils of leaves. The stamens are not in the same position; they are leaves or mo dified bracts, which neither have anything in their axils, nor are in the axils of any other organs. In their origin, they resemble the ordinary bract; later, their tissue swells out, and becomes gradually modified at those points which become anthers. But at any age they are not the less of the nature of leaves (appendices), which is the character of the stamens; whilst in every pistil, here as elsewhere, there are two distinct portions, the one axial, the other appendicular [foliar]. As to the teratological facts, I would say that they may be made to furnish arguments in favour of the most opposite opinions. In this particular instance, however, there is nothing surprising in the cone of an Abies being capable of bearing leaves analogous to those of the branches (Richard, Mém. Conif. pl. xiii.), since this cone bears, normally, bracts or appendages, which are nothing but modified leaves. Conclusions. 1. The female flowers of the Coniferæ differ very little in essentials from one another. They are constructed upon a single type, and were we only to regard these, it would be unnecessary to preserve the divisions of the order of the Coniferæ into Pinaceae and Taxaceæ. 2. The female flower is either terminal, or placed in the axil of a bract or leaf. But it is always (as Schleiden holds) borne by an axis, and never by a bract. Only the form of this axis is very variable; but this is a characteristic of receptacular organs. 3. Thus, as was believed by Mirbel and Spach, this flower is not gymnospermous, but possesses a dicarpellary ovary, without floral envelopes, and containing an erect orthotropal ovule upon a basilar placenta. 4. The cupule, of variable form and consistence, which surrounds this ovary, and which in several genera has received the name of aril, is a later production, although anterior to fecundation, as is the case with all those floral organs, resulting from a secondary expansion of the axis, which we call disks. [A selection from Dr Baillon's numerous and very beautiful figures is given in Plate V.] DESCRIPTION OF PLATE V. Pinus resinosa, L. Fig. 1. A bract (b) detached from the cone, with its axillary scale (a). Fig. 2. The same, further advanced; the scale (a) now presents two lateral lobes or auricles, and a median lobe or apiculus (ml), the termination of the axis of the scale. Fig. 3. Appearance of flowers upon the axis (a); each of them composed of two carpellary leaves (c) of a crescentic form, between which the placenta (p) appears. Fig. 4. The same, further advanced; the carpellary leaves have become connate. Fig. 5. One of the flowers from fig. 4 isolated and more highly magnified; c, carpels; ol, ovule, which appears as the prolongation of the floral receptacle. Fig. 6. Scale much further advanced; the stylary portions of the two carpellary leaves of the ovary (ov) are beginning to become unequally developed. Fig. 7. Flowers, nearly adult, and borne upon the scale, which in length now nearly equals its accompanying bract. Fig. 8. Longitudinal section of an adult flower; the styles (st) are still more unequal than in last figure: ov, ovary; ol, ovule. Cupressus sempervirens, L. Fig. 9. Young flower-bearing branch. The lower bracts (sb) are sterile; the upper bracts, one of which has been cut away (cb), have a centrifugal inflorescence (i), developed in their axils. Note upon the preceding Translation, with Observations upon the Morphological Constitution of certain Abietineous Cones. By A. DICKSON, M.D., Edinburgh.* It is with no little pleasure that I have taken this opportunity of bringing Dr Baillon's remarkable observations under the notice of the Society. By his labours, the morphology of these remarkable plants is now securely based upon the surest of all foundations, viz., that obtained from observation of the different phases of development. I have myself been much interested in this subject, having had my attention drawn to it by the consideration of some abnormal conditions in the cones of the spruce fir. At our July meeting last year (1860) I exhibited and commented upon some "bisexual cones" which seemed to illustrate certain of the relations between the male and female cones in these plants. I then attempted to show that the stamens of the * Read before the Botanical Society of Edinburgh, 10th January 1861. |