536 Gwynne- Vaughan—Remarks on Anatomy of Osmundaceae. 
same evolutionary changes, but much to the contrary. No one, I take it, 
doubts the extra-vascular nature of the ground tissue in the concavity of the 
gutter-shaped leaf-trace. The way in which a leaf-trace originally elliptic 
in section becomes hollowed out adaxially is beautifully shown by that of 
Thamnopteris in its course through the cortex of the stem. 1 This change 
in form is no doubt due to the bilaterality and dorsiventrality of the leaf as 
a whole, and can have nothing to do with the gaps made in the already 
gutter-shaped meristele by the far-away pinnae. Incidentally in the earlier 
leaves of the sporeling of Osmunda regalis the pinna-traces do not leave 
gaps of any kind. They are supplied by strands that are nipped off from 
the extremities of the already gutter-shaped meristele. 
Summary. 
1. The early appearance of axillary pockets of xylem-sheath paren¬ 
chyma in the xylem of the sporeling stele of Osmunda is confirmed. 
2 . The intrastelar origin of the pith in the Osmundaceae is adhered to, 
3. The medullary rays are due to the breaking through of the xylem- 
ring by the xylem-sheath pockets, and are in consequence also intrastelar 
in origin. 
4. The mesarchy found in the basal region of the leaf-trace in Thamno¬ 
pteris and Zalesskya is still occasionally retained in the early leaves of 
Osmunda regalis . 
DESCRIPTION OF THE FIGURES IN PLATE XLIV. 
Illustrating Prof. Gwynne-Vaughan’s paper on the Anatomy of the Osmundaceae. 
Figs. 1-4 are made from drawings, Fig. 5 from an untouched photograph, and Figs. 6-9 from 
under-exposed prints used as camera lucida outlines. 
Abbreviations : l. t. = leaf-trace xylem; prx. = protoxylem ; M. — pith; pkt. — xylem-sheath 
pocket. 
Figs. 1 and 2. Osmunda regalis . Xylem of sporeling showing leaf-trace xylem departing in a 
protostelic manner, x 210. 
Fig. 3. Osmunda regalis » Xylem of sporeling showing simultaneous appearance of the pith 
and of a xylem-sheath pocket, x 210. 
Fig. 4. Osmunda regalis . Xylem of young stem; the xylem-sheath pocket on the left never 
comes into direct contact with the pith, x 130. 
Fig. 5. Osmunda regalis. Xylem of sporeling showing a mesarch leaf-trace and the tannin- 
containing cells in the early pith, x 150. 
Figs. 6, 7, and 8. Osmunda regalis. Meristeles of sporeling leaves with mesarch protoxylem. 
x 150. 
Fig. 9. Osmunda regalis. A mesarch leaf-trace becoming endarch. x 150. 
In the leaf-traces the adaxial side is towards the bottom of the page. 
1 Gwynne-Vaughan : On the Origin of the Adaxially Curved Leaf-trace in the Filicales. Proc. 
Roy. Soc. Edin., vol. xxviii, Pt. VI, No. 29, 1908, p. 433. 
