62 
Eric Drabble. 
cotyledon sheath, which is at this side expanded, while only two 
are found in the much attenuated and partly crushed tissues of the 
other side of the sheath. A ring of small but non-cuticularized 
cells surrounds each bundle, and it is interesting to notice that here 
the parenchyma is comparatively dense with but little air-space 
formation. 
Of the two leaves found within the sheath of the cotyledon, the 
outer is richly supplied with typical bundles. The scleren- 
chymatous sheath is here greatly reduced as compared with that 
of the cotyledonary bundles. A striking point is that while the 
xylem and phloem are well developed in the more internally placed 
bundles, those placed more peripherally show all stages of reduction, 
until finally the peripheral ones consist solely of fibrous elements, 
which are larger in the centre of the bundle and closely resemble 
the vessels and tracheids of the true xylem in transverse section. 
Lignification is densest, and commences earliest in the peripheral 
fibres, and progresses internally in each bundle. Thus all stages 
between the typical bundles and the fibrous strands occur. 
Frequently some phloem elements are found after all true xylem 
has disappeared. A similar condition has been observed in the 
stem of a large tree of Dictyosperma album, 1 where many of the 
fibrous strands contain a few phloem elements. In this connection 
may be noted De Bary’s statement, 2 recently confirmed, 1 that in the 
root of Iriartia occur strands of fibres with a central element 
appearing to be a sieve-tube, but not fully developed. The inner 
leaf is in a folded condition, and the tissues are but slightly 
differentiated. Lignification has, however, set in in a few of the 
bundles, commencing in an endarch manner. No trace of a 
cuticularized endodermis was anywhere found in this region, 
though the test was carefully applied repeatedly. All the parenchy¬ 
matous tissues are here very dense. 
At 8 the structure is essentially similar, but only eight bundles 
are found in the cotyledon sheath, (Fig. 8, v.) The parenchyma of 
the cotyledon sheath is here more richly supplied with air-spaces 
than at 7, and it is very interesting to find again that some of the 
bundles have extremely distinct sheaths of thin walled refractive 
nature, although cuticularization has not set in. 
A section at 9 is closely similar, but the fibrous strands of the 
cotyledonary bundles are greatly reduced, and a third leaf is to be 
seen inside the second, (Fig. 8, iv.) The region between 10 and 11 
1 Drabble. Anatomy of the Roots of Palms. Trans. Linn. Soc., 
1904. 
* De Bary. Comparative Anatomy of the Phanerogams and Ferns. 
