594 
DR JOHN M'LEAN THOMPSON ON 
(15) “ Comparative Anatomy of the Hymenophyllacex, Schizxacex, and Gleicheniace ee,” Annals of Botany, 
xvii, 1903, p. 516. 
(16) “ Studies in the Morphology and Anatomy of the Ophioglossacese,” I, Annals of Botany, April 1913. 
(17) Flora, 1910. 
(18) “On Lepidophloios Scottii," Trans. Roy. Soc. Edin., vol. xlvi, 1908. 
DESCRIPTION OF FIGURES IN THE PLATES. 
(All the figures are from the stem of Platyzoma.) 
Plate I. 
Fig. 1. Transverse section of the stele at the broken base of the small plant described in the text. The 
inner endodermis is a narrow though uninterrupted tube. ( x 50.) 
Fig. 2. Transverse section of the stele at a point in advance of that represented in fig. 1. The inner 
endodermis has been narrowed down to a very slender tube, and scattered tracheides are in the surrounding 
parenchyma. ( x 50.) 
Fig. 3. Transverse section of the stele at a point in advance of that represented in fig. 2. The inner 
endodermis has diminished until it is merely a small group of cells including no pith. ( x 50.) 
Fig. 4. Transverse section of the stele at a point in advance of that represented in fig. 3. The inner 
endodermis has now vanished and a medullated protostele has been formed locally. ( x 50.) 
Fig. 5. Transverse section of the stele at a point in advance of that represented in fig. 4. An almost 
solid protostele has been formed. ( x 50.) 
Fig. 6. Transverse section of the stele at a point in advance of that represented in fig. 5. The pith has 
expanded within' the parenchymatous xylem. ( x 50.) 
Fig. 7. Transverse section of the stele at a point in advance of that represented in fig. 6. An irregular 
endodermal formation has arisen in the growing pith. ( x 50.) 
Fig. 8. Transverse section of the stele at a point in advance of that represented in fig. 7. The irregular 
inner endodermal formation has been resolved into an irregular tube and an isolated group of endodermal 
cells. ( x 50.) 
Fig. 9. Transverse section of the stele at a point in advance of that represented in fig. 8. The inner 
endodermal tube has been ruptured and involves a single chain of endodermal cells. A new tube and sheet 
of endodermal cells have arisen within the pith. ( x 50.) 
Plate II. 
Fig. 10. Transverse section of the stele at a point in advance of that represented in fig. 9. A wide 
though still incomplete inner endodermal tube is indicated and includes an isolated endodermal cell. ( x 50.) 
Fig. 11. Transverse section of the stele at a point in advance of that represented in fig. 10. The inner 
endodermal-cylinder is almost completely differentiated. ( x 50.) 
Fig. 12. Transverse section of the stele at a point in advance of that represented in fig. 11. The inner 
endodermal-cylinder has been disrupted and an irregular endodermal-formation has arisen. ( x 50.) 
Fig. 1 3. Transverse section of the stele at a point in advance of that represented in fig. 1 2. The inner 
endodermal-formation has been resolved into an incomplete tube around a limited body of pith and an 
irregular group of endodermal cells. ( x 50.) 
Fig. 14. Transverse section of the stele at a point in advance of that represented in fig. 13. The pith 
has been greatly diminished and the irregular inner endodermis has become a narrow though incomplete 
tube. ( x 50.) 
Fig. 15. Transverse section of the stele at a point in advance of that represented in fig. 14. The pith 
has been drastically diminished and the inner endodermal tube has been tapered towards a vanishing 
point. ( x 50.) 
