114 



middle, and with a rhomboidal bundle of spmd-vessels (Fig. "V". s.v.) in the 

 thick part of the club. Between these occur three smaller bundles, of an oval 

 form, also constricted in the middle. The central one of these, which is 

 situated just opposite to the interior bundle (Fig. V.c.), is rather more than 

 half the length of the largest, and encloses near its inner end a rhomboidal 

 bundle of spiral-vessels. The othei." two are of the same form as the central 

 one, but not much more than half its length (Fig. V.d.), and the bundles of 

 spiral-vessels, which are also near the inner end, are in section like the 

 sector of a circle, or a boy's kite. The cellular tissue which encloses these 

 bundles is rather lax, and of a light-green colour, becoming close, and densely 

 filled with chlorophyll, towards the outer side. All traces of the inter-cellular 

 passages have disappeared, but in their place two cylindrical bundles of large, 

 loose, translucent cells (Fig. Y.f.) appear near the end of each of the smallest 

 marginal bundles, and these continue to the point of the leaf. The cells that 

 surround the interior bundles, and the rounded interior ends of the largest 

 marginal bundles, are filled with a red fluid, as are also those of the midrib 

 and margins of the leaf. 



The vascular bundles in the free part of the leaf, at the butt, are 

 rhomboidal in section (Fig. "Vl.b.), reaching the epidermis on the outer or 

 inferior surface, but separated by several rows of cells from the inner or 

 superior epidermis; they enclose bundles of spiral- vessels (Fig. "VI. s.v.) that 

 are also rhomboidal in section. Midway between these, and near the superior 

 surface, there sometimes occurs another small cylindrical bundle (Fig. VI. e.) of 

 liber cells, without any spiral- vessels, but more often this is absent. Between 

 each of the vascular bundles there is also a cylindrical bundle of large loose 

 cells (Fig. VI. f), similar to those in the thick part of the butt. The midrib 

 (Fig. VII.) is formed by an elongated bundle of fibres, enclosing a rhomboidal 

 bundle of spiral-vessels near its inner end, and it is surrounded by three 

 circular bundles (Fig. VII. e.) of fibres alone. 



Higher up in the blade, as the free parts of the leaf get larger, the interior 

 bundles of the butt die out, and the medial-sized marginal bundles elongate, 

 until they, as well as the larger ones, reach almost across the leaf (Fig. VIII.) 

 from the outer to the inner surface, the smaller ones (d.) retaining their 

 relative size. All have, however, now altered in shape ; the larger ones are still 

 clavate, but are swollen, instead of constricted, in the middle ; and the swollen 

 pai'ts contain their bundles of spiral-vessels, which neither in shape nor in 

 relative position have changed with the liber-cells. The smaller, or inter- 

 mediate bundles (Fig. VIII. d.) have become more clavate ; but their spiral- 

 vessels have still retained their shape of the sector of a circle. Occasionally 

 on the inner side of the leaf small round bundles (Fig. VIII. e.), composed 

 altogether of fibre, are found, alternating with the bundles that cross the 

 leaf. 



The average thickness of these bundles on the superior or inner surface of 

 the leaf is 0-005 inch, and on the inferior or outer surface, 0-0027 inch, and 

 their distance from one another is 0-018 inch, or fifty-five bundles to the inch. 

 There are, therefore, about two hundred and fifty bundles of fibre in the whole 

 breadth of the leaf, not including the intermediate bundles, which would give 

 about as many more in the lower part of the blade near the butt ; but towards 

 the point of the leaf these intermediate bundles die out, leaving only the large 

 ones, that go the whole way across. These also get finer and closer together 

 the nearer they get to the point, so that there are almost as many of them 

 close to the tip of the leaf, as there are near the butt. On the inferior or 

 outer surface, the bundles of fibres reach to the epidermis, but on the superior 

 or inner surface," several rows of cells intervene. Each bundle of fibres is 

 separated from the next to it, in the interior of the leaf, by a mass of lax 



