170 



THE MARATTIALES 



of the third leaf trace, and at this point there may be seen the base of the third root 

 (r"). Between the fourth and fifth leaf traces is present a section of the first mucilage 

 duct. 5 is a section some distance to one side of the apex, also passing through the 

 primary mucilage canal and the fourth root, which arises between the fourth and 

 fifth leaf traces. Figures C and D are sections on opposite sides of the stem apex 

 from B. The fourth leaf, with its conspicuous stipules (st), shows in these sections, 

 and the third root can also be seen. Fig. 152, C, is a more enlarged view of the 

 third root shown in fig. 151, D. The root is triarch and in the peripheral part of the 

 cortex there is visible a row of very conspicuous cells whose walls stain very strongly 

 with safranine and in section closely resemble large tracheary elements. A longitudinal 

 section of these cells, which are also conspicuous in the later roots (fig. 155), shows 

 that they are elongated sclerenchyma cells whose thick walls are conspicuously 

 pitted. Farmer (Farmer 3) observed similar cells in the roots oi Angiopteris. 



Fig. 154. 

 Two sections of an older sporophyte of D. penman j. Xi8. m, mucilage ducts; jf, stipules of young leaf; r, young root. 



Figures 154 and 155 show three longitudinal sections of a pretty well advanced 

 young sporophyte of £). jenmani. The root (shown in the figure emerging at the 

 base) is probably the second root. The stem has already begun to assume a dorsi- 

 ventral form, and the basal part of the root, which is strongly curved, is cut away 

 and so does not show in these sections. The earliest leaves are no longer recognizable 

 and it is impossible to determine just how many leaves have been formed. The 

 leaves first formed have the single trace characteristic of the first leaves in all of 

 the species, but the youngest leaves show that the leaf trace is double. In this sec- 

 tion (fig. 155, A) is shown a very young leaf, cut through parallel to its surface 

 and showing clearly the stipules at its base and also the young vascular bundles. 

 Within the leaf are two bundles, which are seen to join at its base, but separate 

 again lower down, the two bundles thus forming two distinct traces in the stem. In 

 fig- 154' B, the section passes through the youngest root, which is seen to have its 

 stele joined to one of the leaf traces from the youngest leaf. Several conspicuous 

 mucilage ducts are now present in the stem near the vascular bundles; these are 



