Yapp . — Two Malayan ‘ Myrmecophilous' Ferns . 229 
EXPLANATION OF FIGURES IN PLATES 
X, XI, AND XII. 
Illustrating Mr. Yapp’s paper on ‘ Myrmecophilous ’ Ferns. 
Unless otherwise stated, the figures refer to Polypodium carnosum (Blume). 
The arrows accompanying some of the figures point in each case towards the 
apex of the stem. 
The microphotographs constituting Figs. 5, 12, and 32 were taken by Mr. W. 
Tams of Cambridge. 
PLATE X. 
Fig. 1. Poly podium carnosum , showing its natural habitat. 
Fig. 2. Polypodiu 7 ti sinuosum , ditto. 
Fig. 3. P. carnosum , part of the mass of interlacing rhizomes seen in Fig. 1. 
Fig. 4. Upper part of a single fertile frond. 
Fig. 5. P. carnosum , transverse section through a tunnel leading to the exterior, 
excavated by the ants. 
PLATE XI. 
Fig. 6. P. carnosum, diagram showing mode of branching of stem. a. a. knobs 
of living tissue (incipient- branches). 
Fig. 7. P. sinuosum, ditto, a. a. undeveloped branches. 
Fig. 8. P. carnosum , transverse section of part of the stem near the apex, showing 
an early stage in the formation of the large-celled tissue, (x 42.) 
Fig. 9. Later stage, showing aqueous tissue fully formed. ( x 33.) 
Fig, 10. Section through the aqueous tissue taken parallel to the small-celled 
zone, and cutting transversely several unusually long small-celled projections. 
( x 33.) 
Fig. 11. Ditto, taken close to periphery of aqueous tissue, showing four of the 
pocket-like pits occupied by one or two large aqueous cells. ( x 33.) 
Fig. 12. Microphotograph of a section showing the large-celled tissue breaking 
down to form a gallery. 
Fig. 13. A single branched epidermal hair. ( x 75.) 
Fig. 14. A section through part of a mass of stems, showing the way in which 
the younger stems overlap the older. The galleries are seen cut in various direc- 
tions. b. twig of host tree, (f nat. size.) 
Fig. 15. A transverse section through an old piece of stem, showing the galleries. 
The section also cuts a very short branch longitudinally, at the apex of which is an 
opening (a.) to the exterior made by the ants, (f nat. size.) 
Figs. 16 and 17. Two transverse sections near apex of rhizome. Aqueous tissue 
is still present, v. position of main ventral gallery, (f nat. size.) 
Fig. 18. Horizontal section near apex of leaf-cushion, showing the three blind 
galleries cut across, (f nat. size.) 
Fig. 19. External view of part of main stem, showing the commencement of two 
lateral branches. (Nat. size.) 
