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H. W. RICKETT 
Fig. II. Further divisions in the formation of the germinal disc: &, basal cell. X 150. 
Fig. 12. The same: a, possible apical cell; h, basal cell. X 350, 
Fig. 13. Two sporelings at the time of formation of the germinal disc: sp t, .spore 
tetrad; r, rhizoid; g, germinal disc. X 50. 
Fig. 14. Formation of the germinal disc (compare fig. 13, g). X 350. 
Figs. 15-23. The young germinal disc. X 150. 
Fig. 24. Young thallus continuing its growth in one plane, without formation of a 
germinal disc: a, possible apical cell; sp, spore wall. X 75. 
Fig. 25. Germinal disc in a more advanced stage: a, apical region (the cell contents 
too dense to permit of the cell walls being distinguished); b, basal cell; c, place of attach- 
ment of the germinal disc to the germ tube. X 75. 
Fig. 26. The initial cells at the apex of a young sporeling. X 150. 
Fig. 27. Young thallus growing out in two directions, and possessing two apical 
regions: a, a', apical regions; c, place of attachment of germinal disc to germ tube; b, 
basal cell. X 75. 
Fig. 28. The apical regions of the plant shown in figure 27: a, a', possible apical cells. 
X 150. 
Fig. 29. The point of attachment of germinal disc to germ tube. X 150. 
Fig. 30. Initial cells of a young sporeling. X 150. 
Fig. 31. The same. X 350. 
Figs. 32, 33. The same in shghtly older sporelings, showing the formation of the 
apical notch. X 150. 
Fig. 34. The formation of the apical notch in a lateral position. X 150. 
Fig. 35. Abnormal sporeling from a spore germinated in nutrient solution. X 25. 
Fig. 36. Detail of figure 35. X 150. 
Fig. 37. Another abnormal thallus produced in the same way: a, apical region; 
r, rhizoid. X 75. 
Figs. 38-48. Series of longitudinaF vertical sections through the apical region of a 
mature plant: a, apical cells; ar, archegonia; i, involucres; /, lobes of the thallus; s, mucilage 
hairs. X 350. 
Figs. 49-54. Another series of sections through the apical region of a mature plant, 
cut in the same direction as the preceding: a, apical cells; ar, archegonia; ar in, arche- 
gonial initials; i, involucres; /, lobes of the thallus; 5, mucilage hairs. X 350. 
Figs. 55-61. Series of horizontal sections through the apical region of a mature plant. 
Two sections omitted between figures 60 and 61. The first figure of the series is on the 
ventral surface of the apical region, the last one on the dorsal surface: a, apical cells; ar, 
archegonium; ar in, archegonial initial; /, lobe of the thallus; s, mucilage hairs; x, see 
text; y, possible lobe. X 400. 
Figs. 62-64. Series of vertical transverse sections through the apical region of a 
young plant: a, apical cells; s, mucilage hair; X, see text. X 400. 
Figs. 65-67. Series of sections through the apical region of a mature plant cut in the 
same way as the preceding series, but in a plane not quite perpendicular to the axis of growth : 
a, apical cells; .ar, archegonia; i, involucres; /, lobe of the thallus; s, mucilage hairs. 
X 350. 
Figs. 68, 69. Two plants sketched at intervals of a few days in order to follow the 
origin and growth of the lobes of the thallus. Corresponding letters indicate corresponding 
lobes in each series. The following table shows the time which intervened between succes- 
sive sketches. 
Fig. 68^ March 8. Fig. 69^ March 8. 
Fig. 685 " 13. Fig. 6^B " 12. 
Fig. 68C " 16. Fig. 69C " 14. 
Fig. 68Z> " 19. Fig. 6()D " 19. 
Fig. 69^ " 22. 
Fig. 69F " 28. 
Fig. 70. Plant grown under conditions of excessive moisture, in a petri dish. 
