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568 in Cycadeæ and Coniferæ, published in 1826, I endeavoured to prove that in these two families of plants the ovulum was in no stage inclosed in an ovarium, but was exposed directly to the action of the pollen.

In support of this opinion, which has since been generally, though I believe not universally adopted, the exact resemblance between the organ until then termed ovarium in these two families, and the ovulum in other Phænogamous plants, was particularly insisted on; and I at the same time referred, though with less confidence, to their agreement in the more important changes consequent to fecundation.

I noticed also the singular fact of the constant plurality of embryos in the impregnated ovula of Cycadeæ, and the not unfrequent occurrence of a similar structure in Coniferæ. In continuing this investigation, in the course of the same summer in which the essay referred to appeared, it seemed probable, from the examination of several species of the Linnaean genus Pinus, namely, Pinus Abies, Strobus and Larix, that the plurality and regular arrangement of embryos were as constant in Coniferæ as in Cycadeæ; for in all the species of Pinus here referred to, the preparation for the production of several embryos was equally manifest, and the points or areolæ of production were in like manner disposed in a single circular series at the upper extremity of the amnios.

From these observations, which I have since confirmed in the same and also in other species of Pinus, an additional and important point of resemblance is established between 369] Cycadeæ and Coniferæ; and it is worthy of remark, that while the female organ in these two families exists in a simpler form than in other Phænogamous plants, the normal state of the impregnated ovulum is much more complex, and might even be considered as compound, or made up of the essential parts of several confluent ovula.

On considering the well-known œconomy of several Coniferæ, and especially of the genus Pinus, as at present limited, namely, in their requiring (at least) two seasons to ripen their cones, it occurred to me that these plants, from