56 Lang . — Prothalli of Ophioglossaceae. 
Fig. 54. Vertical section through an almost mature antheridium, showing one 
dehiscence-cell in the wall. ( x 200.) 
Fig. 55. Surface-view of the outer wall of an opened antheridium, showing two 
dehiscence-cells, one of which has broken down. ( x 200.) 
Fig. 56. Vertical section of two antheridia, the wall of one of which shows two 
dehiscence-cells, (x no.) 
Fig. 57 . Vertical section of an unopened archegonium. ( x 200.) 
Fig. 58. Cross section of an archegonium neck. ( x 200.) 
Fig. 59. Median section of the embryo borne on the prothallus shown in 
Fig- 35« f foot, r. primary root, /. first leaf, st. apex of stem. ( x 50.) 
Fig. 60. Apical region of the stem of the embryo in the preceding figure, show- 
ing the form and segmentation of the initial cell. h. hairs in the apical depression, 
l.t. first leaf- trace. ( x 250.) 
Fig. 61. Young plant attached to the prothallus. (Nat. size.) 
Fig. 62. An older plant attached to the prothallus. (Nat. size.) 
Fig. 63. Transverse section of the second root of a young plant, showing 
the position of the mycorhizal fungus. ( x 50.) 
Fig. 64. Transverse section of the stele of the primary root. ( x no.) 
Fig. 65. Transverse section of the stele of the stem below the origin of the first 
leaf, (x no.) 
Fig. 66. One half of a transverse section of this stele more highly magnified. 
en. endodermis, pc. pericycle, phi. phloem, x. xylem,/. pith. ( x 330.) 
Fig. 67. Transverse section of the stele represented in Fig. 65, showing the 
origin of the first leaf-trace. ( x no.) 
Fig. 68. Similar section of another stele, showing the origin of a leaf-trace with 
centripetal tracheides. (x no.) 
Fig. 69. Transverse section of the two vascular bundles at the base of a leaf. 
i.sp. adaxial intercellular space. ( x no.) 
Fig. 70. Transverse section of the stele of a young plant near to the apex, 
showing the first developed tracheides around the pith. ( x 1 10.) 
