Page:The Botany of the Antarctic Voyage.djvu/324

292 be seen on examining a very young anther. The tissue is peculiar and wholly cellular, except just at the base of the columella, whence some spiral vessels descend through the peduncle. A longitudinal section shews the walls of the anther to be remarkably stout and formed of two layers of cells (Plate CIV.f 5 and 6) ; the outer of these are thick-sided, rounded or hexagonal utricles, often filled with a yellow chrornule (Plate CIV.f. 6 and 7) ; the inner on the contrary, are very slender, prismatic, thin-sided cells, densely packed together and radiating from the inner wall of the anther which they line with their bases, and which has no further membrane intervening between these prismatic cells and the pollen. The latter is yellow, globose, and echinulate, like that of other Loranthacea.

The gland, on each side of which the anthers are seated, indicates the position of the undeveloped ovarium in the male flowers; it is very conspicuous in all the species, and in Antidaphne, Pcepp., which, in this respect, does not differ from Myzodendron, although its author has described the filaments as calycine pieces, antheriferous at the apex and the three-lobed gland as a corolla. In Tupeia Antarctica, again, where the segments of the perianth are evidently articulated on the top of the pedicel, the male flowers bear an almost imperceptible prominence in their centre. In Eubrachion the rudimentary ovarium, in the centre of the male flower, is much more fully formed.

In some respects the male flower of this genus resembles that of a species of Gnetum, where a solitary filament, similar to the peduncle of Myzodendron, arises from a sheathing bract and bears at its apex two collateral adnate cells, opening by apical slits which are at right angles to the broad axis of the stamens, (as in Lemna), and contain a central free columella; and where a vascular bundle descends from the base of each anther down the filament. The terminal dehiscence is comparatively rare in one-celled anthers, though seen in Krameria, where the cells coalesce into one. The single-celled anther of M. punctutatum may be further compared with two of those composing the rnultilocular anther of Vucum album, in each of which loculi there is one point from which the pollen-grains are developed; or to one half of the anther of most phaenogamic plants, where the developement of the pollen takes place at two points and in which a ridge is afterwards left in the cell, analogous to the columella in this genus. I much regret not having the opportunity of comparing this with the Castræ falcata, St. Hil., a Braziban plant, allied to Viscuni, but having its pollen developed in the apex of the segments of the perianth. The spuriously one-celled anther of Tupeia? incana (Viscum, Hook. Ic. Plant, t. 73.) is of an entirely different nature. There the two original cells, which are, as in ordinary stamens collateral, open by lateral slits, which become confluent above. This is exactly what happens in Callitriche and many other plants.

I know of no plant exhibiting a structure in the inner cells of the walls of its anther similar to Myzodendron, except perhaps, the Saprium Griffithsii, Br., a transverse section of whose anther, given by Mr. Griffiths, appears to present radiating prismatic cells. The outer layer, again, is a portion of the same cuticle surrounding other more cellular parts of the plant.

. I have only seen the ovarium in Valdivian specimens, apparently of this species, gathered by Mr. Bridges ; figured at Plate CIV.f. 9 and 10. They are sessile, in pairs, in the axil of each bractea. The calyx is adherent with the ovarium and terminates in a thickened ring forming an entire, very short lirnb immediately below the insertion of the style. It is trigonous, and at each angle is a slit, leading to a longitudinal canal that encloses a stout filament, or seta. This seta ascends from the base of the ovarium and gradually elongating, finally escapes from the cavity where it was lodged ( CIV.f 10) ; it is composed of elongated cells cohering by their viscidity. The ovarium is one-celled; the cavity minute and wholly filled by an erect short column, that bears