. / . roe. Sas aaa as 5 YE i gol OR = 
J gS - a * VA ew ~ yeees te > al hee 
pee es SFB a 4 be 2 '¢ be a PS ee athe e rhe aah ee 
le a! / rf 4 
ON ott oe mi 
which consists of fibres, In many plants a ring of cells, often with 
strongly-thickened and lignified walls, the dusdle-sheath, is developed 
either only on the outside of the bast, or round the entire bundle, or 
very commonly round the whole mass of fibrovascular bundles. This is 
especially the case in roots, this layer of cells being there called the 
root-sheath or coleorhiza. ‘The separate cells of this organ areas a rule 
developed in a very characteristic manner, so that for example, the 
various kinds of sarsaparilla used in commerce may be distinguished by 
their means (Fig. 94). 
The further development of the fibrovascular bundles is 
very characteristic of the different classes of plants, as is 
also the arrangement of the various elements on a transverse 
section of a bundle. Fungi, Lichens, Algze, and Characez 
_ have no fibrovascular bundles ; and in Muscinez they are 
either not developed at all or only in a rudimentary man- 
ner. ‘These plants are therefore comprised under the desig- 
nation Cellu/ar Plants or Cellular Cryptogams ; the whole of 
the remainder [Vascular Cryptogams and Phanerogams| 
being on the contrary termed Vascular Plants. 
The fundamental tissue very commonly consists of thin- 
walled succulent parenchyma containmg starch ; but other 
forms of cells may also enter into its composition. In those 
plants which have no fibrovascular bundles the whole of the | 
interior of the plant may be regarded as fundamental tissue. 
In other plants it fills up the spaces between the fibro- 
vascular bundles and within the primary cortex. Even the 
primary cortex, which must, according to the history of 
development, be regarded as a distinct element, is often, 
in consequence of its similarity, treated as belonging to the 
fundamental tissue. Where the fibrovascular bundles are 
closed [Vascular Cryptogams and Endogens] and cannot 
therefore increase in thickness, this tissue is generally de- 
veloped to the greatest extent (Fig. 95,1). In the woody 
portions, z.e, the stem and root, of Conifers and Dicotyledons, 
the fibrovascular bundles of which are open, it occupies a 
less considerable portion of the entire structure. In the 
greater number of such stems it forms a central jr¢A, 
F 2 
T; he Construction of the Plant out of Célls=2 67 : 
