37 
Anatomy of the Ophioglossaceae. 
of the suspensor. It becomes differentiated into a hypobasal half from 
which the foot later arises, and an epibasal half from which the stem-apex, 
first leaf, and probably the first root, are formed. The apex arises near the 
centre of the epibasal tier. 
3. With further growth the shoot becomes vertical and the axis of the 
embryo curved. Further development of the shoot gives rise to the 
hypocotyl bearing the first leaf and apex of the stem. The shoot is at first 
vertical, though dorsiventral in construction. Later its apex bends over 
and growth proceeds horizontally. 
4. The relative positions of suspensor and embryo, and of the organs 
of the embryo, are compared for Marattiaceae, Ophioglossaceae, and Seed- 
Plants, and it is suggested that the suspensor represents the last trace of the 
filamentous juvenile stage in development of the plant, and may have 
persisted in the Seed-Plants from their filicineous ancestry. 
DESCRIPTION OF FIGURES IN PLATE III. 
Illustrating Prof. Lang’s paper on Hel m inthostachys. 
All the figures are from untouched photographs. 
Photo. 1. Young embryo ( e ) still unsegmented but extending down into the prothallus ; f ‘ foot 
of plant on the same prothallus. x 140. 
Photo. 2. Older arrested embryo showing the upper tier of the suspensor (j 1 ), the second tier 
of the suspensor (s 2 ), and the embryo proper (e). The segment walls of the embryo are broken 
down, but a number of nuclei are visible, x 158. 
Photos. 3, 4. Two sections of a prothallus bearing a plant (e 1 ), the younger embryo of inter- 
mediate age (e 2 ), and the young arrested embryo (<? s ) figured in Photo. 2. s 1 , upper tier of suspensor 
of the intermediate embryo ; s 2 , second tier of suspensor. x 40. 
Photo. 5. Horizontal section of the embryo proper of e 2 more highly magnified, hyp, the 
hypobasal tier ; ep, the meristematic epibasal tier, x 158. 
Photos. 6-9. Four sections of the second intermediate embryo shown in Text-fig. 3, B. The 
junction of the second tier of the suspensor {s 2 ), and the embryo proper {e) is seen in Photo. 6 ; Photo. 7 
shows the hypobasal half of the embryo proper giving rise to the foot. In Photo. 8 the base of the 
vascular cylinder is seen with the first tracheides (tr). Photo. 9 passes through the apex of the stem 
which is marked with a cross, x 158. 
Photo. 10. Obliquely transverse section of a mature embryo showing the well-preserved suspensor 
{s 1 , s 2 ). x 40. 
Photo. 11. More highly magnified figure of this suspensor. j 1 , upper tier ; s 2 , lower tier, x 158. 
Photo. 12. Transverse section of a prothallus bearing a young plant attached by the suspensor, 
the two tiers of which are seen at s 1 and s 2 . x 40. 
Photo. 13. Section of the suspensor of another young plant in relation to the prothallus. Both 
tiers of the suspensor are multicellular, ar, archegonial neck ; s 1 , upper tier of suspensor ; A lower 
tier, x 158. 
