454 Bower . — Studies in the Phytogeny of the Filicales . 
shoot, shows very similar results. Sections at various levels from its apex 
downwards are seen in Fig. 12, I-VI. The first (i) shows the young axis with 
a complete solenostele, and laterally the lowest leaf of the shoot is attached, 
with its leaf-trace divided into five strands. In II the solenostele has opened, 
and the leaf-trace, now reduced to four strands, is moving towards the leaf-gap, 
which it joins first by one margin (ill), finally by both ; but even after this 
is accomplished the divisions of the leaf-trace into separate strands may 
remain (iv). Later the ring is completed (v). Passing downwards the 
solenostele contracts, and the central pith is reduced until it finally dis- 
appears, together with the internal endodermis (vi). The central mass of 
soft tissue has the appearance of phloem, but isolated tracheides are not 
uncommon near its margin (Fig. 13). Towards the base of the shoot the 
soft tissue becomes still more reduced. In essentials this behaviour is as in 
Metaxya and Lophosoria , but at the base of the bud the stelar structure is 
of a more primitive type than in those Ferns. 
A still more interesting type is seen in Thyrsopteris elegans , which has 
already been shown to have a truly marginal sorus, with the first sporangia 
springing from the very apex of it (‘ Land Flora,’ p. 588, Fig. 329). As the 
vascular structure of Cibotium and Dicksonia is now fairly well known, it 
seemed desirable to obtain like facts for Thyrsopteris also, since that Fern 
has sori so like those of the Dicksonieae, though in some ways more 
primitive than they. The plant shows in less degree than Dicksonia the 
dendroid habit : it is in fact a stunted type of Tree-fern. The published 
descriptions of its habit are not very explicit. Kunze (‘ Die Farrenkrauter,’ 
p. 3) says that ‘the stem or root-stock is hitherto unknown’. Hooker 
(‘ Species Filicum,’ i, p. 64) describes it as ‘ arborescent ? ’, and quotes Kunze’s 
remark that ‘this Fern is said to have a caudex as thick as a walking-stick, 
whence it is supposed to be arborescent Diels, however (‘ Nat. Pflanzenfam.,’ 
i. 4, pp. 122-3), describes the stem as attaining ij metres in height, but as 
thick as the thigh, and closely covered by the scars of old leaves. Christ 
(‘ Farnkrauter,’ p. 331) quotes the same words, but adds that no trace of 
a creeping rhizome is present. There are now well- developed plants growing 
in Kew and in Edinburgh, and smaller specimens in other collections. In 
Glasgow we have some received by gift from the Edinburgh Botanic 
Garden, for which I record my thanks to the Director, others obtained by 
purchase. 
The fact that a strong bud may come above ground at some distance 
from the parent plant, as seen at Kew and in Edinburgh, indicates the 
presence of a ‘ runner * like those of the Cyatheoids. One of the young 
plants given from the Edinburgh garden was shaken out from the soil, and 
showed a massive piece of axis, about 2 inches long, from which arose two long 
thin runners, with stunted leaves and long internodes. One of these had 
come above ground, and bore foliage leaves. The insertion of the runners 
