16G 
PROFESSOR W. C. WILLTAMSOFT OX THE ORGAN FSATIOX 
Plate. 
Fig:. 
10 
11 
12 
Pagfes on wliicli 
references are 
made to the 
fig:ures. 
parts of a still lower verticil of tire same organs. 
Cabinet number, 1000. X 40. 
A section through a branching fragment of Rachiopteris 
hivsuta : A, oblique longitudinal section through a 
portion of a stem or branch; a, a large vascular 
bundle composed of beautifully reticulated or pitted 
vessels ; 6, V, cortical layers ; B, a second bifurcating 
branch of the same group ; a, the vascular axis also 
dichotomosing and comjDOsed of a mixture of barred 
and reticulated vessels or tracheids, the latter resem¬ 
bling those of A, a; 6, the inner cortex correspond¬ 
ing to A, h" ; A, outer cortex, like A, 6; a 
zone of somewhat thickened prosenchymatous cells ; 
c, a transverse section of a small lateral outgoing 
branch, similar to a second one at d. At ^ is a 
transverse section of a corticated branch or root, 
with a vascular bundle in its centre, surrounded 
by two layers of a cortex, apparently like h" and V 
oh the branch B ; g and g, external cortical surfaces 
densely clothed with large curved multicellular 
hairs. Cabinet number, 1847. Xl4. 
The clusters of hairs between the points g and g 
further enlarged. X43. 
Transverse section of a branch of Rachiopteris hirsuta ; 
a, the central vascular axis composed of reticulated 
tracheids ; c, a zone of delicate parenchyma enclosed 
within 6, which latter seems closely to resemble a 
bundle-sheath; g, g , g", g", four radiating appendages 
passing outwards from the supposed bundle-sheath, 
h, through the bark. These are probably roots. 
Cabinet number 1845. X 40 . 
Obliquely tranverse section througli another branch of 
Rachiopteris hirsuta passing through the central 
vascular bundle at a ; h, the apparent bundle-sheath ; 
c, the zone of the probable phloem; d, d, d', three ■ 
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160 
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