FROM THF, USUAL STRUfTURK OF SEEDS. 303

There are some cases in which this early opening of the ovarium, instead of being, as in the preceding instances, an irregular bursting, apparently caused by the pressure of the enhirged ovula, is a regular dehiscence in the direction of the suture. Of this Stcrculia phdamfoVia and /V. colo- rata are remarkable examples; their foUiculi after opening, which takes place long before the maturity of the seeds, acquiring the form and texture of leaves, to whose thickened marghis the ovula continue firmly attached until they ripen. Another example of this early and regular dehiscence occurs in an imdescribed genus of the same family, which differs from SfercuUa jy/r/^<^/;^//b/2<2 in its pericarpium having a terminal wino- and a sinji;le seed.

In the specimens of a plant lately sent from Brazil by [i« Mr. Sellow, I observe a similar economy. In this case the ovarium, which is originally unilocular W\i\\ five parietal placentae, soon after fecundation opens regularly into five equal foliaceous valves, to the inner surface of each of which an indefinite number of ovula are attached.

The genus Reseda, whose capsule opens at top at a very early period, may be considered as affording another in- stance, though much less remarkable, of the same anomaly. And it is possible that this may be the real structure in certain cases of which a very different view has been taken.

In the instances of naked seeds now given, the bursting of the pericarpium precedes the distinct formation of the embryo, while the proper coats of the seed remain entire till after its separation from the parent plant, and germi- nation has commenced.

It may not be uninteresting to contrast this economy with that of the Mangroves and other plants of tropical countries, which grow on the shores, and within the influence of the tide. In many of these the embryo, long before the seed loses its original attachment, acquires a very considerable size; and the first efiect of this un- usual development is the rupture, in most cases succeeded by the complete absor])tion or disappearance, of the proper integument of the seed. In some instances the develop-

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