FIBROIN E. 



[ 323 ] FILAMENTOUS STRUCTURES. 



upon the action of a ferment (see Froy, 

 HM. 1(5, and -M. Baker, IViys. !J8). 



Till' tibrinons plasma of the lower animals 

 resemble?: tibrine in man^' re.-<pects, but does 

 not separate in tibres. 



FIBiiOINE. — The principal cliemical 

 constituent of silk, cobwebs, and the horny 

 skeleton of sponges ; but the latter is now 

 considered to be composed of a new sub- 

 stance, spomiine. In the pure state, it is 

 white, insoluble in water, alcohol, ether, 

 acetic acid, and ammonia. 



Bmr,. That of CHinrisTRY, animal. 



FIBRO-PLASTIO TISSUE. See Tis- 

 sue, nnno-PLASTic. 



FIBROUS and FIBRO-VASCULAR 

 BrXDUP]S. See Tissuks, vegktable. 



FIBROUS STRUCTURES of Plants. 

 — This terra is somewhat equivocal, and 

 requires a little explanation here. In com- 

 mon laujiiiage all vegetable substances are 

 termed fibrous which can be separated into 

 more or le.-s line threads possessing a certain 

 degree of tenacity ; special examples are 

 furnished by those forming the materials 

 for textile fabrics. But the anatomical or 

 microscopical structures comprehended here 

 are exceedingly varied, including not only 

 liber-fibres, but spiral vessels, and even 

 hairs. Thus, Flax (PI. 28. fig. 2) is tlie 

 liber of Linum usHatissimum ; Hemp (PI. 

 28. fig. 6) of Cayinahis ; Jute (Pi. 28. fig-. 3) 

 of Corchorus capsuJaris kc. ; Puya (PI. 28. 

 fig. 26) of Bcehnieria Puya, and the material 

 of Chinese gi-ass cloth (PI. 2^. fig. 2o) of 

 Bahmcria nivea; Coir (PI. 28. fig. 4) the 

 liber-like fibre of the husk of the cocoa-nut; 

 Manilla hemp (PI. 28. fig. 7) of the fibro- 

 vascular bundles of Musn textilis ; New- 

 Zealaad flax of Phormmin tenax ; Espar- 

 to grass of Lijgeum esparto ; and Cotton 

 (PL 28. fig. 1) consists of the hairs covering 

 the seeds of species of Gossypium. These 

 and similar substances are also spoken of 

 under Liber, Hairs, and under theii' re- 

 spective heads. 



In botanical language, the word fibre has 

 come into use in two very different senses. 

 First, any long cell attenuated to a point 

 at both ends, and with its walls thickened 

 with ligneous secondary deposits, is called a 

 Jihre by some authors. Thus the term woody 

 fbre is applied to the shorter cells of this 

 kind which make up the substance of most 

 solid woods; while the term liher-Jibve is 

 applied (with more justice) to the often 

 extremely elongated wood-tubes which form 

 the elements of the liber of Dicotyledons 



and the woody part of the fibro-vasfular 

 bundles of the Monocotyledons. (See Tis- 

 sues, VEGETABLE.) The characters of 

 structures of this kind will be given under 

 Liber and Wood. Secondly, the term 

 Jihve is applied to the secondary deposits 

 upon the walls of cells, vessels, ducts, &c., 

 which, instead of forming continuous pitted 

 layers, take the pattern of spiral or analogous 

 lines, and, by increasing in consistence, sub- 

 sequently form real fibres, often elastic and 

 unrollable, of firmer substance than the 

 cell-wall upon which the}^ Avere originally 

 deposited. The numerous modifications of 

 these^6ro2M clepodts upon the walls of cells 

 are spoken of under the heads of Spiral 

 Structures, Vessels, and Secondars 



DEPOSITS. 



It must not be omitted here that the walls 

 of many cells and liber-fibres, which appear 

 at first sight to be composed of homogeneous 

 laminpe, may often be made to exhibit spiral 

 streaks, by the use of reagents and macera- 

 tion ; indeed they present themselves during 

 the natural dissolution of the membranes 

 of some of the OsciUatoriacec'e (Aixactis, 

 ScHizosiPHON — PL 8. figs. 13, 15). Hence 

 some authors have recently recurred to the 

 old notion that all vegetable membranes are 

 formed of fibres cemented or blended toge- 

 ther. This is again strongly combated by 

 others, as regards the primary membrane of 

 cells. We enter more particularly into the 

 details under the article Spiral Struc- 

 tures fif Plants. 



FI'CUS, Linn. (Figs). — A large genus 

 of Urticaceae (Dicotyledons), some of which 

 possess a remarkably thick epidermis and 

 curious pseudo-glandular structures con- 

 nected with it. Ficus elastica, one of the 

 plants j'ielding india-rubber, now commonly 

 grown in pots in rooms, is a good example. 

 The clavate bodies (PL 48. fig. '27) of Meyen, 

 developed in cavities in the leaf, beneath 

 the epidermis, contain crystalline deposits. 

 (See Glands and Raphides.) 



FILAMENTOUS STRUCTURES op 

 Plants. — This name would be more appli- 

 cable than fhroiis strncfures to such sub- 

 stances as Cotton, which consists of elon- 

 gated hairs (PL 28. fig. 1), and indeed to all 

 elongated cellular filaments with thin and 

 collapsing walls. It would include aU long 

 vegetable hairs, like those forming the 

 coma on many seeds (Poplars, Asdepias, 

 Gossypium, Sec.) ; also those forming felty 

 coatings on the epidermis, as in many Com- 

 posita), &c. It is also applical)le to the 



y2 



