112 



of a paper on the same subject, read by Mr. Nottidge, to the Philosophical 

 Institute of Canterbury. Not having as yet had the pleasure of reading this 

 paper, I am not able to refer further to it ; but judging from the very short 

 abstract that appeared in the papers, we seem to be pretty well agreed uj)on 

 all points, except as to the existence of small canals in the fibro- vascular 

 bundles, formed by the inter-spaces between the ultimate fibres, Avhich, I 

 venture to suggest, must have baen caused by the knife tearing apart the 

 bundles of fibres, when making transverse sections. 



Development of leaf. — The young leaf of the Flax plant (Phormium tenax), 

 when about a quarter of an inch in length, is composed of loose parenchy- 

 matous tissue, covered both on the inner and outer surfaces, near the centre, 

 by an epidermis of elongated rectangular cells, the edges of the leaf being 

 crenulated by the jutting-out of the young growing cells. Imbedded in this 

 cellular tissue lie about twenty-three vascular bundles, eleven on each side of 

 the midrib. These, in this young state, are composed entirely of spiral-vessels, 

 which contain a single spiral fibre, easily unrolled with a needle. These 

 bundles are 0-0013 inch broad, and about 0-004 inch apart from one another. 

 (Fig. I.) They lie longitudinally in the leaf, towards the central part of it, 

 the outer growing edge being composed only of cellular tissue. The upper end 

 of each bundle runs into that lying next to it towards the centre, and they 

 thus get shorter and shorter as they recede from the midrib. When the leaf 

 gets about an inch long, the vascular bundles are still seen to branch and 

 anastomose with one another (Fig. IT.) ; but this soon ceases, and at all later 

 stages they are very nearly parallel, converging slightly towards the point of 

 the leaf. A layer of thin elongated tubes now makes its appearance, 

 surrounding the bundles of spiral vessels. This is the first state of the fibres 

 from which the plant has got its celebrity ; but as yet they are exceedingly tender, 

 and break with the slightest touch. When, however, the leaf has attained a 

 length of four inches, the fibres in the upper part of it have acquired 

 considerable strength, while those at the base are still quite weak. When the 

 leaf is about nine inches long, it commences to exude gum, and appears then 

 to be fully formed. 



Description of full-grown leaf. — When fully grown the leaf attains a 

 length of from three to ten feet, according to soil and variety. The colour 

 varies from light yellow-green to deep blue-green, with yellow or red margins 

 and midribs, while the lower part of the leaf is usually pink. In shape the 

 leaf is lineai'-lanceolate, and keeled, with an acute point. At a point rather less 

 than half way down from the tip, the two superior or inner surfaces of the two 

 halves of the blade begin to coalesce at the midrib, and this coalescence 

 gradually increases until one-half of the leaf is joined together. The coal- 

 escence then gradually decreases, until it occupies only about a fourth of the 

 breadth of the half blade, which breadth it keeps to the bottom of the leaf, the 

 two half blades being closely appressed as far as the base, where the two 

 marginal edges closely overlap one another, and form a sheath through which 

 the younger leaves grow. It is only the inner surfaces of the lower portion of 

 the leaf, below the place where the coalescence of the two half blades begins to 

 decrease, that exude gum. 



For the sake of convenience, I shall, in this paper, call the upper part of the 

 leaf, the blade ; that portion where the coalescence of the two half blades 

 reaches its maximum, and which is about half-way between the two ends of the 

 leaf, the butt ; and the lower portion, the base of the leaf. 



The full-grown leaf is composed of parenchymatous tissue, in which fibro- 

 vascular bundles lie imbedded, and remain isolated from one another as fibrous 

 cords, some of which ran from one end of the leaf to the other. This cellular 

 tissue is covered, on both surfaces of the leaf, by an epidermis composed of 



