Anatomy of the Ophioglossaceae. 23 
suspensor (.y 2 ). In D the lower end of the suspensor (.y 2 ) is seen to be 
continuous with an oval mass of cells belonging to the embryo proper 
(e2), and the following sections only show this, their level being below 
that of the suspensor. At the level passed through in E the embryo 
proper is seen to consist of two tiers, the limit between which is indi- 
cated by the dotted line. Still lower sections (f) miss the terminal or 
epibasal tier of the embryo and indicate that the hypobasal tier bulges down- 
wards. If the figure of the reconstructed embryo (Text-fig. 3, a) is 
considered in the light of the separate sections it will be clear that it 
consists of the upper tier of the suspensor (.y 1 ), composed of a single large 
Text-fig. 4. Outline figures of a number of transverse sections of a prothallus bearing a young 
plant ( e i) ; an embryo of intermediate age ( e 2) ; and a young arrested embryo ( e 3). j 1 , s - 2 , first and 
second tiers of the intermediate embryo ; e 2, the embryo proper, s , the cavity once occupied by the 
suspensor of the plant, x in f, position of root apex of the plant. 
cell ; of the second tier of the suspensor (.y 2 ), which in this specimen is much 
elongated and composed for the most part of a row of cells ; and of the 
globular embryo itself (e), which is enlarged downwards where the foot 
is developing. The epibasal tier with the apical region is opposite the 
cross, and it will be evident that the embryo is as yet straight in that 
the epibasal tier is not directed upwards. 
PI. Ill, Photo. 3 shows the appearance of the elongated suspensor 
(A, s 2 ), while Photo. 4 is of a section passing through the embryo proper (e 2 ) 
at a level which traverses both the hypobasal and epibasal tiers. A similar 
section of the embryo is seen more highly magnified in Photo. 5. As this 
shows, the lower or hypobasal tier (hyp.) is composed of larger cells not 
presenting a meristematic appearance, white the small terminal tier ( ep .) 
