T J S 



504 



T I S 





veloped. This tissue maybe divided into two kinds, ge- 

 nuine and spurious ; the genuine being that in which tin- 

 fibre is distinctly marked on the inside of the cell, and the 

 spurious that in which the fibre, either by absorption or 

 the union of its various parts, forms rings, bars, dots, and 

 other appearances on the sides of the cell. The genuine 

 fibro-cellular tissue is mostly found in parenchymatous 

 and prosenchymatous cells. It lias been known for a long 

 tune amongst botanists, and was first described by Hedwig, 

 who was followed by Moldenhawer and others. Th. 

 hbumlant in the external parchment-like layers of aerial 

 roots of Orchidaceie, and nave been described by Mcyrn 

 in Oncidium altissimum. Acropera Loddigcsii. Hni.-sav ola 

 cordata, &c. They occur in the hairs of the pericarp of 

 many of the Composita-, as in Perdicium taraxaci, Se- 

 . flaccidus, and Trichocline humilis. Horkel has de- 

 .-cribed them in the epidermis of many Labials-, us Zizi- 

 phora, Ocymum, and many Salvi>. The seed-coats of 

 many plants possess them, as Gilia Ipomopsis, Polemonium 

 ( 'anfua, and Caldaria; and Kippist has lately demonstrated 

 their presence in many of the species of Acanthaceae. In 

 some of these cases, and many others might be mentioned, 

 the fibre appears to constitute the whole of the cell, as 

 Mated under fibrous tissue. 



The fibre in these cells varies in its position and form. 

 In the cells of the leaf of Oncidium altissimum they are 

 v cry distinct, and occasionally branched. In the testa ol 

 the seed of Maanandya Barcleyana, where thcv were first 

 pointed out by Lindley, the fibres run in different direct ion- 

 ovcr each other, forming a network. In the endothecium 

 of Calla a-thiopiaca they are parallel, and in this form are 

 eomimm in the Mime onran of other plants. Jn the 

 endothccium of Nymphza alba the fibres form regular 

 arelies arising from a plane base. In the elaters of .Inn- 

 trermnnnia and in the testa of Acanthodium the cells arc 

 iy elongated, with a silicic spiral fibre in their inte- 

 rior. 



The spurious fibro-ccllular tissue includes the porous 

 and dotted cells of many authors ; the rcllultr pnrosee et 

 i:iiitr/nltf> of Link. If a portion of the parenchyma ol 

 Viucum album be examined, the inside of the cells will be 

 found to possess a number of bright spots. They were first 

 discovered by Treviraiuis in C'ycas revoluta, and supposed 

 by him to be granule-. Tln-y \\ere thought by other 

 observers to l>e pores: hence their name porous cells. 

 Sprengel, Mold, and Link consider them little vesicles, 

 but Meyen has given a different explanation of theii 

 nature. He ascribes their existence to a metamorphosis 

 "f tlr Derated in cell*. They are ol ten met with 



in the name cells an fibres, and it is by the union of some 

 part* of the fibre and the absorption of others that tin 

 space* are produced, which when tirsl viewed appear at> 

 though they were granules, pores, or vesicles. Tin 

 appearance i* frequently found in the various forms ol 

 fibre- vascular tissue, where there can be little doubt of tin 

 spots arising from the irregular formation of the 

 hren thow botanists 

 on this point with regard to cellular 



rectneM in vascular Uue. As it must be admitted thai 

 there U no essential ditleiem-e between the cellular am: 

 vascular tJMues, it is undoubtedly a correct inference thai 

 these spoU have the same origin in both ti- 



A transition from porous e,-iU to porous tubi-.-t is seen ii 

 the tiwue which has been called IJothrcnchyma. In this 



Usuc, which can be well seen in I'hytorrene, as well a* 



cas, a number of truncated porous "eel Is an placed oiu: 

 on the other no as to form arvln: . mbe 



>y the absorption or rein- ;.:irlitions. 



Porous vascular t :.nvd to tins form by l.indley 



imler the n;i <tinuous Hothrenchyma, as'thc pur 



jtions or union of the cells are not visible. When the, 

 joints of union of the cells are evident, lie calls it articu- 

 lated Hothrenchyma. 



Dotted cells have their walls marked with dark spots, 

 l -ei-n observed in the pith of ('alvcanlhus 

 loridus and in the stem of Drac;i>na terminal!*. They ap- 

 jiear only to ilitt'er from the porous cells in the- matter from 

 which they are fornn trreater opacity, and not 



transmitting the liiiht so fr, 



l'ilirii-i-iiM-iil<ir Ttxmi". or Trnrhrtn-hijiiin rxvi xjiii- 

 of Link), consists of tubes, in the ii: nch spiral 



fibres are generated. The fibres of this tissue, like the 

 last, are subject to metamorphosis, the consequence of 

 which is, the tubes present the appearances of nngs, bars, 

 and bright and dark spots. 



The tubes consist of a very delicate membrane, which is 

 mostly cylindrical ; it may MweTer UBUM a pnsmatical 

 form when the tubes are in bundles and closely pr< 

 together, as in ferns and many monocotyledonous plants. 

 The fibres generated in this tissue are mostly comprised, 

 and wind up the sides of the tube in aspiral form. \Vhen 

 the membrane i* broken, the fibre in most cases may be 

 unrolled. It is in the younser tubes that this is most , 

 effected ; as in the older tubes those changes sro on which 

 connect the membrane and the fibre firmly together, and 

 convert the latter into bars, dots, cc. fhe numl" 

 fibres included in a tube varies; it is frequently single, 

 but in some instances as many as twenty-two have been 

 counted. They have no fixed direction ; some pas- limn 

 right to left, others from left to right. Some difference of 

 opinion luis existed as to whether the fibres are tubular or 

 not. Schleiden says in most instances they are solid, but 

 where they are formed from large globules of jelly they 

 appear to be tubular in both vascular and cellular ti 



Link divides fibro-vascular tissue into grunt in- and 

 spurious; the former includes all those re*ad* which 

 possess perfect fibres. The principal forms of 

 the xjiiral, aiinulur, and niiuiilijnriii vessels. The 

 (CAM'/ consists of a tr.be, m which one or more fibres run 

 continuously along its sides from one end to the other. 

 (ti,e,f, Fig. 4.) When the fibres are single, they are called 



Fig. 4. 



: when there is more than one. ciinijn>ini<l. The 

 spiral vessels are most abundant in young plants, as their 

 character becomes changed by :n;e.' When the fibres ad- 

 here to the sides ol" the membiaiie, they are said to lie 

 The spiral vessel v\ as at one time considered a 

 veiy important tissue, performing especial vital functions, 

 the circumstance of air being frequently found in 

 them, and this air containing a larger quantity of oxyjren 

 than the atmosphere, they were supposed to cany on tin- 

 function of respiration. Subsequent observation "however 

 proves that they as frequently convey liquid as air. and 

 Meyen supposes that they are only filled with nir when a 

 larger quantity of fluid ceases to be required by the plant. 

 Anntiliir ri'Mi'/x or </urt.\ consist ol tubes with perfect 

 nni_ r s of fibre on their sides, (g, 1'ig. 4.) These arc evi- 

 dently formed from the interruption of the spirit, and the 

 union of the broken ends, as they are lieqm-ntly found 

 t with a spiral fibre m I: be. They are 



mostly larircr than the spiral vessels, and the fibre is also 

 thicker: they arc very abundant in mouocotylcdonouij 



