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 570 ON THE PLURALITY AND DEVELOPxMKNT

duction or separation of a distinct body within the nucleus of the ovulum, which, before impregnation, is a sohd uniform substance.

370] In this stage the upper extremity of the included body, or amnios, is slightly concave, and has a more or less rough or unequal surface ; the inequality being in consequence of the laceration of the cellular tissue, by which it was in its early stage attached to the apex of the original nucleus, or rather to a short cylindrical process arising from it and corresponding in size and form with this concave upper extremity, from whicb it separates when the amnios has attained its full size.

On this concave upper extremity of the amnios a few minute points of a deeper colour, and disposed in a single circular series, are sometimes observable ; in general, how- ever, they are hardly to be distinguished.

Below the concave apex the amnios itself is slightly transparent for about one fourth of its length, the remain- ing, portion being entirely opake.

On dividing the whole longitudinally it is found to con- sist of a pulpy cellular substance, in which no definite cavity is originally observable ; the upper transparent portion is, however, of a looser texture, and on the included embryos becoming manifest, a cavity irregular both in figure and extent is formed in its centre.

But before the embryos themselves or their funiculi become manifest, the areolae, or portions of the substance destined for their production, are visible.

These areolae, as 1 observed them in the conniion larch in May, 1827, are from three to five in number, of nearly cylindrical form, arranged in a circular or elliptical series, and are seated near the apex, with which they probably communicate by the similarly arranged points of its surface already noticed.

In the amnios of Piniis si/lvestrisy as observed in June and July last, the corresponding parts were found con- siderably more advanced. In the specimens then examined, the remains of the embryoniferous areolae, from four to six in number, were still visible, but consisting of conical mem-

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