54 Lang . — Prothalli of Opkioglossum pendulum 
EXPLANATION OF FIGURES IN PLATES 
I, II, AND III. 
Illustrating Dr. Lang’s paper on the prothalli of Opkioglossum and 
Helminthostachys. 
PLATE I. 
Opkioglossum pendulum. 
Fig. i. Young prothallus viewed from the side (a), “from above ( b ), and from 
below (c). ( x 25.) 
Fig. 2. Slightly older prothallus seated on a fragment of tissue in the humus. 
( x 25-) 
Figs. 3, 4. Prothalli, showing the origin of the first branches, (x 25.) 
Figs. 5, 6. Mature prothalli seen from above ; that shown in Fig. 6 is the 
largest found. ( x 7. ) 
Fig. 7. Portion of a branch of one of the larger prothalli more highly magnified, 
showing the smooth apical cone, the unicellular hairs, and the antheridia. ( x 80.) 
Figs. 8, 9. Young prothalli in longitudinal section, (x 70.) 
Fig. 10. Median longitudinal section of the apex of a branch, showing the 
segmentation of the initial cell. ( x • 200.) 
Fig. 11. Transverse section of a similar apex, (x 200.) 
Fig. 12. Longitudinal section of a branch of the prothallus. ( x 25.) 
Fig. 13. Transverse section of a branch, passing through the region in which 
infection by the Fungus is taking place, (x 70.) 
Fig. 14. One of the unicellular hairs in vertical section. ( x 200.) 
Fig. 15. Diagrammatic section of an old prothallus, passing through the organic 
centre and traversing two branches longitudinally ; the regions inhabited by the 
endophyte are shaded, an. antheridia, ar. archegonia. 
Fig. 16. Part of a transverse section of a branch, showing the entrance through 
a hair of an infecting hypha of the Fungus. ( x 200.) 
Fig. 17. Two cells of the prothallus containing the vesicular swellings of the 
Fungus, n. nucleus, h. hyphae, v. vesicles. ( x 750.) 
Figs. 18, 19, 20. Three stages of development of the antheridium represented in 
vertical section, (x 375.) 
Fig. 21. Vertical section of an almost mature antheridium from a transverse 
section of a branch. ( x 375-) 
Fig. 22. Tangential section through the outer wall of a mature antheridium, 
showing the triangular opercular cell, (x 375-) 
Fig. 23. Vertical section of an opened antheridium from a longitudinal section 
of a branch. The shading indicates the tissue inhabited by the endophyte. 
( x 200.) 
