papyrifera | .. | ·7–2·1 | .. | 3·6 | | | | _Linden bast._ Tilia grandifolia | .. | 1·1–2·6 | .. | 1·5 | | | | C. Fibro-vascular bundles | | | | | | | | _New Zealand Flax._ Phormium tenax | 80–110 | 2·5–5·6 | ·8–1·9 | 1·3 | | | | _Aloe._ Aloe perfoliata | 40–50 | 1·3–3·7 | 1·5–2·4 | .. | | | | _Esparto._ Stipa tenacissima | 10–40 | 0·5–1·9 | ·9–1·5 | .. ---------------------------------------------+-------------+-----------+-----------+--------- A very important point in the diagnosis of a raw material, and next in order of treatment, is the degree of purity of the substance, in so far as this is related to structure. The fibres may be associated with cellular tissue, or with cellular debris, if they have undergone the retting process or other treatment for separation; or with “encrusting and intercellular substances” in various proportions. In the latter case the association with the fibres is usually much more intimate; they are in fact essential constituents of the fibre _bundles_ {40} (bast-fibres, fibro-vascular bundles), whereas the former we may regard as “foreign matter.” We may, however, distinguish between the normal incrustation of the fibre-cells, and such an incrustation of the filaments as would be described as a loose adhesion of non-fibrous matter. The latter is seen in such tissues as the bast of the adansonia, and the fibro-vascular bundles of the aloes. These are points with which observation alone can familiarise the student; as experience grows he will find it increasingly easy to follow _general_ distinctions, and in proportion as he uses his own faculties, so he will be able to generalise for himself. He will find this equally true of the second section of the microscopic examination, i.e., the micro-chemical diagnosis of fibres. Under this head is included the observation of the behaviour of fibres towards the various reagents above described. In addition to their microscopical employment it is useful to note their effect on fibres in the gross, both in their natural state and after treatment with bleaching agents.