16 BOTANICAL GAZETTE [juLy 
have been turned in a similar way to face laterally outward (s pc, 
fig. 23). The slight depression thus formed on the ventral sur- 
face (sc, figs. 23, 24) is the beginning of the soral canal, which 
grows constantly deeper as the capsule develops (jigs. 24-26), 
becoming crescent-shaped in cross section (figs. 27-30), and 
finally closing at the outer end, by the growing together of sec- | 
tions V and VI, to completely inclose the sporangial cells (jigs. 
26-32). 
By the striking change in the external form of the capsule 
already mentioned, the position of the sori within this is con- — | 
siderably affected. From their origin ( fig. 7¢) we might expect — | 
the sori to face the median wall, as in Marsilia, but this is not the — 
case, for in accommodating themselves to the globular form of 
the capsule, the sori of the upper pair soon come to face inward 
and downward, while those of the lower pair face upward and 
inward (jigs. 27-29), or, in other words, all four face towardthe 
central axis of the capsule. | 
When fully developed to sporangium mother cells the deriva- _ 
tives of the marginal cells are elongated perpendicularly to the — 
surface of the sorus, densely filled with contents, and have large — 
nuclei in which, in the resting stage, the chromatin is collected | 
in a few rounded masses (figs. 26-28). The number of sporan- 
gium mother cells in the length of the sorus is ten or more ( /ig- 
26), while the number seen in transverse sections varies from 
four to five at the base or top ( figs. 27, 30) to as many as twel 
at the middle (fig. 29). 
The basal cells of the sorus are the first to form sporangia 
( fig. 26), and this begins in each of them by the occurrence of 
inclined walls, cutting out a tetrahedral apical cell (sf, figs. 26 
28, 29). One or more series of segments are cut off from thi 
off the tapetum in the usual way (s 4, figs. 28-30). 
to Meunier, who has carefully described the development of the 
sporangia, the microsporangia and macrosporangia are just alike 
up to the time of formation of the mother cells. This view i$ 
