Yapp . — Two Malayan ‘ Myrmecophilous ’ Ferns . 231 
Fig. 41. Polypodium nigrescens. Diagrammatic section through a sunken sorus, 
to show its similarity to that of P. carnosum. 
Fig. 42. P. carnosum. Diagrammatic sections showing successive stages 
(a. b. c. d.) in the reflexing of the soriferous lobes. 
Fig. 43. P. carnosum. Part of a fertile leaf-segment, showing reflexed position 
of mature sori. ( x about 3. ) 
Fig. 44. P. carnosum. A sporangium. ( x 92.) 
Fig. 45. P. carnosum. A sterile leaf-segment, bleached by Eau de Javelle, 
and stained to show venation. ( x 3.) 
Fig. 46. P. carnosum. Part of a fertile leaf-segment treated in the same way. 
The sorus-cup is diagrammatically represented as if no flexion had occurred, 
(x 8.) 
Fig. 47. P. sinuosum. Part of a fertile frond, to show venation, s. sorus. 
( x 3-) 
Fig. 48. P. sinuosum. Part of a sterile frond. ( x 3.) 
Fig. 49. P. carnosum. Developing stomata, taken from an upper leaf-segment 
of a young frond, a. b. c. d. successive stages. ( x 197.) 
Fig. 50. A mature stoma, (x 197.) 
Fig. 51. P. carnosum. Part of a transverse section through a leaf-segment. 
a. layer of large colourless cells beneath the upper epidermis. ( x 246.) 
