Anacrogynous Jungermanniales. 219 
side of the middle line. The plant grows near the sea, and 
periodically becomes buried in the sand, forming a tuber in which 
food is stored (Fig. 43). The leafy portion of the plant dies down, 
1. a m 
Fig. 42. PetalopJiyllum ral/sii. Mil, Successive transverse sections of 
the stem, x20; m, mycorhizal zone. IV, Part of I, x 50, showing fungal 
hyphae traversing the rhizoids and ramifying in cells of mycorhizal zone. 
V, Two cells containing hyphae, x 350. 
Fig. 43. Petalophyllum ralfsii. I Longitudinal section through apex of 
of stem, showing the tuberous swelling (T) behind and below the growing- 
point (G.P.). II, Transverse section of growing-point, showing the apical 
cell (X). On either side are the young leaves (L.); below are two mucilage- 
hairs in cross-section. Ill, Part of a longitudinal section through the 
growing-point. L., leaves; M.H., mucilage-hairs. IV, Two cells in the tuber, 
showing densely granular contents. I, x 20 ; II, III, xl50; IV, x 350. 
