484 ' SECQKDARY CHANGES. 



Like the latter they proceed from the longitudinal division of an elongated spindle- 

 shaped tissue-mother-cell of the cambial zone, without any transverse divisions. In 

 the thick-walled forms, a subdivision of the lumen into compartments may subse- 

 quently occur, by means of thin transverse walls, as is the case in the chambered 

 sclerenchymatous fibres (p. 134) : these are septate fibrous cells. 



The elements in question, as follows from what has been stated, are products of 

 the cambium, in which the cellular qualities persist permanently, or disappear slowly. 

 In their further characteristics they are closely related to the other elements of the 

 wood, namely, on the one hand, to the woody fibres, and on the other to the short- 

 celled parenchyma. Of the two subordinate forms which result from these relations, 

 the former may be termed fibrous cells in the strict sense, while the latter may bear 

 the name of intermediate cells'^ (Ersatzfaserzellen) given by Sanio. 



a. The former agree in their form, and in the structure of their walls, with the 

 woody fibres, and thus certainly take part in the functions of the latter, into which 

 they may gradually pass over completely. They are distinguished from them by the 

 nature of their contents. The latter almost always contain starch (comp. p. 115): 

 in Spirsea salicifolia Sanio found traces of chlorophyll ; this appears more abundantly 

 in the septate fibrous cells of the one-year-old wood of Vitis vinifera and Centradenia 

 grandifolia. Tannin is contained in the fibrous cells of Vitis, and traces of it in that of 

 Syringa vulgaris, while in the other woods investigated it is absent in these elements, 

 even where it occurs in other cells. 



In the wood of Punica Granatum, all the elements of which, with the exception 

 of the vessels, are filled with starch ^ the grains contained in the fibrous cells are 

 on the average considerably larger than those of the other cells. 



Besides the plants already mentioned fibrous cells containing starch occur in the 

 wood of Berberis vulgaris, Mahonia Aqulfolium, Begonia muricata, angularis, Sambucus 

 nigra, racemosa, Cheiranthus Cheiri, Salix cinerea (root), Ligustrum vulgare, Syring* 

 vulgaris, Clematis Vitalba, species of Acer, Vitis vinifera, Celastrus scandens, Euonymus 

 europaeus, latifolius, Hedera Helix, Acacia floribunda, Robinia pseudaeacia, Ficus elastica, 

 rubiginosa, Sycomorus, Rhus Toxicodendron, Tamarix gallica ; fibrous cells with slightly 

 granular contents occur in Ephedra. 



Septate fibrous cells occur in Coleus IVTacraei, Hydrangea hortensis, Fuchsia globosa, 

 Aucuba japonica, Celastrus scandens, Euonymus latifolius, europaeus, Spiraea salicifolia, 

 chamaedryfolia, Ceratonia, Hedera Helix, Pittosporum Tobira, Eugenia australis, Rubus 

 idaeus, Justicia carnea, Ficus Sycomorus, rubiginosa, elastica, Bignonia capreolata, Tectona 

 grandis, Rhus Cotinus and Toxicodendron, besides the plants already mentioned ; either 

 the non-septate predominate (e. g. Spiraea salicifolia), or the septate, e. g. Vitis, Hedera, 

 and Punica. Starch has always been found in the septate cells, although in small quantities, 

 except in Punica and Ceratonia. In the case of Justicia carnea only, Sanio states that 

 he found the cells containing air, ' no doubt abnormally.' 



b. Sanio's intermediate cells'^ (Ersatzfaserzellen) (Fig. 205, p. 480), agree with the 

 short-celled parenchyma of the ligneous bundles which will be next described, in all 



' [In justification of the use of the term ' intermediate cells ' in place of a more strict translation 

 of the terra 'Ersatzfaserzellen ' introduced by Sanio, it may be pointed out that, though the inter- 

 ■ mediate cells do replace the short-celled parenchyma in some few cases, that is not their constant 

 character. It is thought that the use of the term ' intermediate cells ' will avoid this difficulty, while 

 it brings the real character of the cells more prominently forwai-d, viz. that they are intermediate mjorm 

 between fibrous and short parenchymatous cells; compare Sach's Textbook, 2nd Engl. Ed. p. 950] 

 " A. Brann, /. f. ; compare p. 471. 



