The structure & development of the mosses and ferns (Archegoniatae) . e in some degree associated with the increase in size of the roots.^ According to Holle ^ the four-sided apical cell found in the stem of the young sporophyte is retained permanently, but in Angiopteris this is not the case, as in the older sporophyte a single apical cell is not certainly to be made out. Bower ^ 1 Holle (2), p. 217. ^ It is possible that a single initial may be present even here, but the great similarityof the central group of cells makes this exceedingly difficult to Holle, p. 218. * Bower
The structure & development of the mosses and ferns (Archegoniatae) . e in some degree associated with the increase in size of the roots.^ According to Holle ^ the four-sided apical cell found in the stem of the young sporophyte is retained permanently, but in Angiopteris this is not the case, as in the older sporophyte a single apical cell is not certainly to be made out. Bower ^ 1 Holle (2), p. 217. ^ It is possible that a single initial may be present even here, but the great similarityof the central group of cells makes this exceedingly difficult to Holle, p. 218. * Bower (ii), p. 324. IX MA RA TTIA CEyE—ISOE TA CE^ 269 comes to the same conclusion as Holle, although in an earlierpaper ^ he attributes a single apical cell to the stem of Angi-opteris. The stem in both genera becomes very massive, butits surface is completely covered by the persistent arrangement of the bundles is like that of Ophioglossum,and they form a hollow cylinder with distinct meshes corre-sponding to the position of the leaves. The bundles are,. Fig. 141.—Marattia Dati£-lasn (Baker). A, Cross-section of the ultimate rachis of a fully-developedleaf, X 26; B, part of the vascular bundle of the same, X 200; C, coUenchjma from the cortexof the same, Xiso; D, cross-section of the lamina of the cotyledon, X200; .ly, xylem. according to Holle, concentric, but the phloem more stronghdeveloped upon the outer side. The thick petioles of the full-grown leaves are traversed b}^very numerous vascular bundles, which at the base give offbranches that supply the thick stipules within which theybranch and anastomose to form a network. These bundles inA^igiopteris are arranged in several circles, or according toDe Vriese and Harting,^ the central ones form a spiral. Inthe rachis of the last divisions of the leaves, however, both of ^ Bower (2), p. 579. - Holle (2), p. 217. ^ De Vriese (i). 270 MOSSES AND FERNS CHAP. Marattia and Angiopteris, there is but a single axial bu
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