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the other posterior to the wood, the former constituting the fibres of the liher, between wliich and the wood
all new layers of the latter are placed. The three or four succeeding layers of wood are accompanied in Myzo-
dendron with bundles of pleurenchj-ma (P late CVII. ter, f . 1 , / ) , aud Link figures occasional fibres similar to
those of the liber situated witWn the wood of Viscum. In many other particulars the structure of the wood of this
genus and Viscum is very similar, as in the form the alburnum assumes (f. 1, c) ; in the narrow tubes containing
a spiral vessel that occurring at the ioner margin of the layers, which they thus sepai-ate, forming in Viscum,
as here, an obscure medullary sheath. The tissue of the wood itself, (which is much modified in the different
species of this genus, as I shall hereafter shew,) in the present species consists of longer tubes, whose walls,
though very much more delicate than those of Viscum, probably are similarly perforated.
In some respects this disposition of tissues may be compared, though not strictly, with that of Menispermacea,
so beautifully illustrated by M. Descaisne.* After the stem of Cocctdus laurifolim has attained a certain age, a
second deposit of wedges of wood is formed externally to the liber, but without any additional liher. In Myzodendron
the two wedges are deposited within one year of each other, the second witliin the first, and both are annually
augmented by new matter ; in both wedges however, the deposit of pleurenchj-ma similar to that of the hber, which
accompanies every layer for the three or four first years, is withheld from all future layers.
Wood o f other species. The above-described structure of the wood is, with slight modifications, common to all
the species of the group Eumyzodendron. Though I am quite unable to make so satisfactory dissections of that of
M. punetulatum, from the very remarkable density and minuteness of its- tissues, I stdl am inclined to consider that
its greatest peculiarity, the occupation of the position of the medulla by pleurenchj-ma, is a modification of what
occurs in many Loranthaceoe, and is owing to the existence of a second or inner deposit of pleurenchyma similar to
that of the liber, which in this species instead of being arranged in separate concentric bundles, is collected into one in
the axis of the stem. Hence in the section of the stem of a leaf or flower-bud (P late CVII. te r,f. 8 .), this tissue
is seen to be present instead of the pith, and the great density of the wood of the older stems may, in a
measure, be due to thé incompressible nature of this tissue, and to the rays (which cannot he called medullary)
being also formed, not of cellular tissue, but of pleureuchj-ma deposited with the scalariform in very small quantities.
Of the other Eumyzodendrons there are three whose tissues I have examined, aud added figures of aU, except
M. ohlongifoliuni, which hardly differs from M. hrachystachyum.
In M. quadriforum, DC., (P late CVII. ter, f . 6 and 7,) there is generally but one series of wedges of wood,
the second being reduced to a single wedge, lying obliquely across the axis of the stem; the vessels of the liber are
exceedingly inconspicuous ( / . 6, i) the cellular tissue, bark, and pith large and loose, and the tubes formmg the wood
very large and few in number ; the smaller tissue interposed between the layers (e) is conspicuous. In the old
stems I cannot detect the inner layer of liber. The alburnum (c) has the appearance of compressed cellular tissue.
I have not met with woody cells in this species.
I n J I . ZiM€anyb?i«OT,DC.,thereisbutone series of woody plates (P late CVII. ter, f . 3, 4 and 5). The cellular
tissue is large and loose, and contains both in the bark and medullary rays, numerous conspicuous masses of
woody cells ( / . 3 and 4, a). Both series of vessels of plenrenchj-ma ( / . b and g) are large. Those of the scalariform
tissue are of a greater diameter than in any of its congeners, cylindrical, constricted, (as in bothrenchjona)
and septate at intervals equal to their breadth ( /. 0. «) : the tubes of the medullary sheath and those interposed
between the layers of wood are of very unequal diameter and constricted here and there ( / . 5. b).
Wood o f Fagus. To P late CVII. is added a sketch of the wood of Fagus Forsteri;— / . 11 represents a
transverse slice from a branch five years old, the letters denote the same tissues as in / . 5, 6, 8, 9 and 1 0 . From
* Decaisne, Mémoire sur la famille des Lardizabalées ; in Archives du Muséum d’Hist. Nat. vol. i. t. 10.
/ . 12 , wlüofi is taken from a brancfr of Faxjus six years old, it will be seen that tbe duets,^ dotted and otherwrse
mmked vessels are large and abnndant, and tbat tbe cbief difference between / . 12 , and a s.rmlar section of on
wedge of ilyzodeuiron hrachystaxhyum f . 6, lies in the sealarifonn vessels being disproportionately abnndant in tbe
latter, and not being scattered amongst the pleurenchyma.
Xamiñcatiou. In this, as in M. punetulatum, the terminal internodes bear, towards tbeir upper part several buds,
each opposite the axil of a leaf; of tbese the leaf-buds elongate aud become new, permanent internodes; the flower-
buds fall away. In the former species (Plate CVII. b k ,f. 1) the flower-bnds were near the apex of tbe mtemode,
and two frequently becoming developed into branches, tbe ramification was oonseqncnUy dichotomons. In
M. hraohystaclyum (Plate CVII. bis, f . 7) tbe flower-buds are generally the upper, and ihe ramification hence
alternate.
The vaginal enclosing the unprotraded buds are vertically two-lipped, and formed from the bark wUeb encloses
a large cavity commnnieating almost with the axis of the stem where the bud is developed. The dehiscence
is spontaneous, before tbe included organ has advanced snffioiently to force a passage. The relation of P / *
to those of a germinating embryo is clear; tbe cavity in tbe internode eontainmg the bud is analogous to that m
the cotylcdonary extremity of the embryo inelmUng the plnmnle, whose course in germmation is thus imitated by
the buds as often as tbe plant developes them.
Germination. I have been able to watch the progress of germination in this species and to follow the eonrse
of the radicle from the time of its leaving the pericarp, till it has frdly established itself upon the tree it affects.
Several ofthe ripened seeds, still enclosed in thefr pericarps, are generally detached together from the parent plant,
they adhere by their viscid filaments and are carried by tbe birds, winds, or other natural causes, from one tree to
J t h e r , where they may often be seen banging entangled amongst the leaves and twigs. Tbe gram is placed almost
in contact with the stem ; it is immaterial to which surface. As I have not seen young T H y r a f e t a attached to
old trunks aud branches, I presume the young plant can only pierce a compai-atively newly fonned bark. The
elongation of the eaffiieide pushes before it tbe disk and style, whieh fall away, and the radicle always escapes at
this point and protrades beyond the pericarp, to whieh the embryo remains attached until the parasite has gained a
firm lodgment on the tree. The embiyo now generaUy becomes curved, the elongating caulioule seeking the nearest
point of the beech, whieh it finally reaenes. At this period the cotyledons, distinctly swoUen, are stdl eontamcd in the
shi-ivelled albumen, and a very evident notch marks their point of union (P late CPI. / . 6). l^he ladicle now
expands like tbe mouth of a trumpet, is concave and has become a compound body, consisting of three distmet
parts 1 st, a membrane continuons with the surface of the canlionle, which expands honzontaUy over the cutio e,
is riutinons, and is the first immediate cause of adhesion between tbe bark and the parasite. 2nd. A tlnek fleshy
she°ath whose convex margins touch the bark. 3rd, A cnsbion-shaped body in the axis of the radicle, which is
pressed arainst the bark and is destined more immediately to convey nourishment from the tree to the fu nre
fidl-vroivn parasite. At P late CVI. / . 4, is a germinating seed, with the eotyledonaiy extremity stdl enclosed m
the aUnnnen. and the radienlar expanded as it appears on reaching the bark ; / . 6 represents the same attached, with
the albumeE removed, sliewing the uotcli of the cotyledons.
If a lonritudinal section of tbe embjTO be now made, (as at P l a t e CV I./. 6) there will be seen, 1st, at the
base of the cavity ill t h e cotylcdonary extremity, two excessively minute green bodies, whieh, at a later period.
become developed Into the first pair of leaves, ai-e pointed upwards towards the notch at the union of the cotyledons,
and escape by the rupture of the membranes that enclose them; 2nd. spiral vessels descending from the base
of these which are lost in the cellidar substance of the cushion-shaped body (Plate CVI, / . 7) ; 3rd. a longitudinal
line indicating a future separation of the cotyledons and outer substance of the embryo the latter forming
an inteoTiment that includes the plumide, cushion-shaped body and its snn-onnding sheath. This central mass
included between tbe plumule above and base of tbe cushion below, is tbe growing portion of tbe future plant, aU
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