THE OLDER SPOROPHYTE 179 



to the plerome cylinder, while from the outer cells of the meristem group arise the 

 new cells for the root cap. The outer segments cut off from the peripheral cells of 

 the apical group of cells undergo more rapid periclinal divisions than those nearer 

 the center and the cells thus formed contribute to the cortex of the root. 



Unlike the roots of most of the Ophioglossaceae, those of Dancea branch 

 freely in a monopodial fashion. This is paralleled among the Ophioglossaceae by 

 some of the larger species of Botrychium, Helminthostachys, and Ophioglossum 

 pendulum. Kiihn's statement that the roots are unbranched is incorrect. The 

 branching of the roots was perhaps somewhat more frequent in D. jamaicensis 

 than in D. elliptica, but the latter species also shows numerous short lateral rootlets. 

 The root hairs are not conspicuous on these older roots, but are readily seen upon 

 the younger ones and are then found to be multicellular, as was first shown by 

 Brebner for D. simplictfolia. Sections of the larger roots were examined in these 

 two species and, while they agreed in the main, there were some slight differences. 

 In a large root of Z). elliptica, about 2 millimeters in diameter, the outer portion was 

 occupied by about four rows of brownish thin-walled cells, very probably more or 

 less suberized. Within this was a ring of brownish sclerenchyma cells about three 

 cells in thickness, and between this and the exceedingly conspicuous endodermis was 

 a broad zone of parenchyma, the cells containing much starch. A short distance 

 outside of the endodermis was a ring of conspicuous mucilage ducts. There were 

 twelve xylem rays alternating with as many rays of phloem. These did not extend 

 to the middle of the stele, which was occupied by a pith of considerable size. 

 The roots of Z). jamaicensis were somewhat smaller and the main differences were; 

 first, the thicker layer of tissue outside the ring of sclerenchyma, which was much 

 less developed than in D. elliptica (in many places this ring was but one cell in 

 thickness and very seldom more than two cells); second, the mucilage ducts were 

 relatively very much larger; third, there were but nine xylem masses instead of the 

 twelve in the root of Z). elliptica. 



The endophyte, which is usually found in the primary roots of all the Marat- 

 tiaceae is generally wanting from the larger roots of the adult sporophyte. 



THE SPOROPHYTE OF KAULFUSSIA. 



The development of the young sporophyte in Kaulfussia resembles that of 

 Dancea in most respects, but from the first it is markedly dorsiventral, like the 

 sporophyte oi Helminthostachys. The cotyledon, while not provided with the char- 

 acteristic free stipules of the later leaves, still has its base connected with a ridge 

 which extends around the stem apex and youngest leaves, which thus lie in a cavity 

 at the base of the cotyledon in much the same way that the stem apex is situated in the 

 young sporophyte of Ophioglossum; but the sheath in Kaulfussia forms a shallow 

 open cup, instead of the closed conical sheath found in Ophioglossum. This stipular 

 sheath seems to be in all respects similar in its origin to that found in Ophioglossum. 



The second leaf lies nearly opposite the first and the third next to the first, 

 and so on, the distichous arrangement being evident from the beginning. We have 

 already pointed out that in the very young sporophyte the vascular bundle from the 

 cotyledon is continued directly into that of the root and that the bundle from the 

 second leaf joins this common bundle, as shown in fig. 163. These primary bundles 

 run on one side of the apical meristem, which, as in Dancea, is of very Hmited extent 

 and does not contribute at all to these bundles. 



The apical cell of the young sporophyte, up to the oldest stages that were in- 

 vestigated, is very much like that of the very young plant and is broader than that 

 oi 'Dancea, more resembling both in cross and longitudinal sections the apical cell 



