187 
and Growth of Monocotyledons. 
greater consistence which the older parts of the stems of Palms 
acquire is to be regarded as arising from causes similar to those 
producing the peculiar characters of the heart-wood of Dicoty- 
ledons. 
DESCRIPTION OF THE PLATES. 
Plate IX. 
Fig. 1. A branching rhizome of Sparganium ramosum, exhibiting the nodes, 
a, and the internodes, h ; in the latter the fibro-vascular bundles 
take straight and parallel courses. 
Fig. 2, Half of a vertical section through a terminal bud, showing the re- 
lative positions of the developing bundles, a, the central paren- 
chymatous region, in which the bundles lie ; h, the line where the 
fibrous layer is formed by the lower extremities of the bundles ; c, 
the cortical region in which lie the liber (?) bundles ; d, the punc~ 
turn vegetationis. 
Fig. 3. A similar section ; the references are the same ; e e are nascent 
roots (figs. 2 and 3 are magnified six diameters). 
Fig. 4. A portion of the cortical region with liber (?) fibres continued into 
the leaves. 
Fig. 5. Vertical section of a full-grown node (like a of fig. 1), prepared by 
maceration, so as to exhibit the fibro-vascular bundles in sihi. a, 
the bundles ; b b, axillary branches forming the internodial por- 
tions (like b in fig. 1) ; c, the cortical region, now a mass of fibres ; 
d, the fibrous layer, which presents several layers of densely inter- 
woven fibres derived from the lower extremities of the bundles of 
the central region. 
Fig. 6. Transverse section of an internode (b in fig. 1). a, the central re- 
gion ; 6, the fibrous layer ; c, the cortical region, here very much 
developed. 
Fig. 7. Vertical section of the same, a, &, c, same references ; d, a root, the 
central fibro-vascular bundle of which is seen arising from the 
fibrous layer. The root breaks down the substance of the cortical 
region when making its way out. The fibro-vascular bundles of 
the stem are parallel here, and the slender liber (?) bundles are 
shown in the cortical region c. 
Plate X. 
Fig. 1. Highly magnified vertical section of a bud. a, the nascent fibro- 
vascular bundles. 
Fig. 2. Transverse section of a portion of an internode, a, the central re- 
gion ; c, the fibrous layer giving off the vessels to the root g ; d, the 
cortical region ; e, liber (?) bundles ; /, epidermis (enlarged about 
five times). 
Fig. 3. Part of the same highly magnified, a, the parenchyma of the central 
region of the stem gradually becoming converted into ligneous 
cells as it passes into the centre, 6, of the fibro- vascular bundle of 
the root ; c, the ducts which are given off from the fibrous layer to 
form the vessels of the root ; d, the cortical parenchyma of the stem. 
Fig. 4. Magnified section of the cortical region, showing the large inter- 
cellular spaces (the cells of this tissue are extremely irregular in 
form, and contain no starch granules), e, a liber (?) bundle. 
