488 
Notes . 
STUDIES m THE MORPHOLOGY OE SF ORE-PRO- 
DUCIIG MEMBERS: PART III. MARATTIACEAE. By 
F. O. Bower, Sc.D., F.R.S., Regius Professor of Botany in the 
University of Glasgow 1 . 
The memoir, of which this is an abstract, deals with the sori of all 
the four living genera of Marattiaceae ; the development has been 
traced in Angiopteris and Marattia from the earliest stages to 
maturity, in Danaea and Kaulfussia from such early condition as the 
material would permit. Some of the results from Danaea have been 
already submitted to the Society in a preliminary statement 2 . One 
result of the investigation has been to demonstrate, as regards their 
development, the substantial unity of type of the sporangia in the 
four genera. In all of them a single ‘ superficial parent cell ’ of 
prismatic form is to be recognized embedded in the massive sporan- 
gium when young, not in a central position, but directed obliquely 
towards the centre of the sorus. By periclinal division this forms 
internally the archesporium, externally that part of the wall where 
dehiscence takes place. The tapetum arises, typically in them all, 
from the cells surrounding the archesporium. The dehiscence is in 
all by a slit in a radial plane, which may widen to a circular pore 
in Da?iaea. In those sori where the sporangia are united laterally 
there is no annulus; it is present only where the sporangia are 
separate, as in Angiopteris. 
An interesting feature is disclosed by estimates of the potential 
spore-production of the single average sporangium in the four genera ; 
the results in round numbers are, in Angiopteris 1,450, in Danaea 1,750, 
in Marattia 2,500, in Kaulfussia 7,850. It is to be remembered 
that the usual numbers in Leptosporangiate Ferns are 48-64; in 
some Leptosporangiate Ferns ( Osmunda ) the number may rise to 500. 
I have ascertained in Gleichenia , however, that the number may be 
as high as in Angiopteris. This large potential output of spores 
goes parallel with the broad base of the sporangia ; in fact, the 
Eusporangiate condition is that best adapted for maturing large 
numbers of spores in the individual loculus. 
Frequent deviations from the type have, however, been observed, 
as well as variations of size and mode of segmentation of the 
sporangia, and it is not possible in certain cases to refer the whole 
1 Abstract of a paper read before the Royal Society, June 17? 1897. 
2 Roy. Soc. Proc., vol. lix. p. 141. 
