;68 
Notes . 
* 
two or three bundles are approximated together with their xylems 
mutually directed towards each other, to produce what is really the same 
result, viz. a concentric strand ; in fact, all the strands are variations 
of one and the same type of structure, viz. the concentric. The 
bundles mostly exhibit, like those of the central cylinder, an inverted 
portion on their dorsal side, and this latter in its turn may have a small 
normally-orientated strand in close proximity to its outer face. Bun- 
dles, usually of collateral structure, are seen here and there between 
the two rings : these are the connecting-strands between the central 
cylinder and the outer concentric bundles 1 . 
Fig. io. Welwitschia mirabilis, Hk. — Part of transverse section of the stalk of 
the female inflorescence, showing the concentric strands of the second vascular 
cylinder, r 2 (Diagrammatic). r\ central cylinder, x, xylem ,ph : phloem. 
Here and there is a very small bundle, collateral in structure and 
with normal orientation, lying within the central cylinder in the pith. 
Another striking part of the structure consists in the presence and 
enormous development of what I feel, although with some hesitation, 
inclined to regard as the representative of centripetal xylem ; it occurs 
1 For similar strands connecting two cylinders see my paper : ‘The Comparative 
Anatomy of certain species of Encephalartos ,’ Trans. Linn. Soc., vol. v, pt. 14, 
1900, Fig. 2. 
