THE FERNS 133 
groups of sporogenous cells are much less definite than 
in Ophioglossum, and do not have a separate opening 
for each; still it is quite conceivable that the simple 
sporangia of Ophioglos- 
sum may have originated 
from structures not unlike 
the groups of sporogenous 
cells found in the Antho- 
cerotacez. 
In the ferns, as in the 
mosses, each sporogenous 
cell gives rise to four 
spores, which develop in 
an absolutely similar way, 
and offer another striking 
proof of the close rela- 
tionships of the two 
groups. 
If we admit that Ophio- 
glossum shows the most 
primitive type of spo- 
rangium among the ferns, 
we may say that passing 
from this type to that 
found in the most special- 
ized ferns, the so-called 
“ Leptosporangiate,” we 
Fic. 34 (Eusporangiate Ferns).— A, 
sporophyte of an adder-tongue fern 
(Ophioglossum vulgatum) ; sp, the 
sporangial spike; B, longitudinal 
section of the sporangial spike 
of another species (O. pendulum), 
showing the cavities containing the 
spores; C, cross-section of the spo- 
rangial spike of O. pendulum; D, 
separate sporangia of Botrychium; 
E, leaflet of Marattia, showing the 
synangia, or coherent sporangia; F, 
a single synangium cut to show the 
separate sporangial cavities; G, 
Angiopteris, one of the Marattiacez 
with nearly separate sporangia, sp. 
encounter an almost perfect series of intermediate forms 
leading up to the exceedingly specialized sporangium 
of the latter, and this series may be assumed to rep- 
resent the evolution of the sporangium of the lepto- 
sporangiate ferns from the simpler type found in 
