SPOROPHYTE. 17 



cortex readily breaks across and pulls loose from the much more tough and 

 elastic vascular core. The outer surface is of a dark reddish-brown color, 

 shading' to nearly white at the apices. In very rapidly growing- rhizomes 

 the soft white apical region may be 2 cm. long-, but usually it is about 

 5 mm. Glabrous to the unaided eye, the mature parts of the rhizome may 

 be seen with a hand lens to be scattered over with the bases of dead hairs. 

 At the apex the hairs themselves are very numerous and serve to clothe 

 the soft parts with an efficient protective covering- (fig's. 70, 106). Scales 

 are entirely lacking- from all parts of the plant. 



The leaves are inserted without articulation, mostly alternately to rig-ht 

 and left of the mid-line on the dorsal surface of the rhizome. They stand 

 therefore in two dorso-lateral rows.* Since the distances between them 

 rang'e from 1.6 cm. to 5.7 cm. (usually about 3 cm.), we may speak of 

 definite nodes and internodes (fig-. 3) (</. Boodle, and Gwynne-Vaug'han). 



Branching" occurs in two ways: direct forking- of the rhizome, and occa- 

 sional stem-buds given off from the lower parts of the petioles (figs. 3,4). 

 The latter will be discussed in connection with the leaf. A fork gives all 

 the appearance of a true dichotomy, the two branches spread equally, like 

 the arms of a Y, from the parent axis, and a ridg'e runs over the crotch 

 (fig-. 99) from dorsal to ventral surface of the stem. In young- stages 

 (arms 1 to 2 cm. long") the two branches are alike in length and diameter, 

 but inequalities of growth soon cause them to differ. I did not determine 

 how the two initial cells originate. 



The interesting and beautiful concentric structure of the stem (fig. 67) 

 was evidently known to De Bary (1877, 1884), and was thus described by 

 Eaton (1879): 



The section shows a broad exterior ring of light-brown parenchyma; inside of this 

 is a broad circle of minute white starch-cells, then scalariform vessels in a narrow ring, 

 bordered by other minute cells, which are most probably bast cells; inside of this is an- 

 other broad circle of starch-cells and in the very center is a roundish mass of brown 

 sclerenchyma. The whole section has such a regular concentric system that it is not 

 only very pretty to look at, but would be very well suited for anatomical study in the 

 classroom [p. 341]. 



Gwynne-Vaughan (1903) also says: 



A perfectly solenostelic vascular system was found in the stems of all the species 

 included in the following list: Davallia hirsuta, marginal:*, strigosa, platyphylla, 

 hirta, spelunccc, novce-zeylandia, Lindsay a retusa, Dicksonia apiifolia, ctcutaria, scabra, 

 punctiloba, davallioides, Pteris scaberula, incisa,ludens, Pellcea atropurpurea,falcata, 

 fatnesonia imbricata. All these ferns have a creeping, more or less dorsiventral rhizome, 

 with the leaves arranged in two rows on the upper surface, and their solenosteles differ 

 from each other and from that of Loxosoma as described in Part I of this paper [1901] 

 in so slight a degree that the same description will serve for them all [p. 691]. 



*Of 134 leaf-bases on stems which were taken at random, 96 insertions were dorso- 

 lateral (right or left), 21 directly on one side (right or left), 16 dorsal, and 3 ventral. 

 Each ventral leaf springs from the angle of a fork of the stem, and bends upward 

 through the fork. 



