264 
ORGANOGRAPHY. 
BOOK I* 
The type of Marsileaceae, properly so called, may be taken 
from Marsilea itself, of which the most complete account has 
been given by M. Fabre. 
In Marsilea Fabri the fructification consists of a two-valved 
coriaceous involucre [sporocarpium, Endl.), having its valves 
held together by a central line continuous with the stalk : 
this involucre seems to be a modified leaf. From the stalk 
there rises a mucilaginous ring, to which adhere minute ra- 
mifications of the spike, terminating in oblong spikes covered 
with fructification. After a time the mucilaginous ring 
detaches itself from the stalk at one end, straightens, and 
carries up with it the spikes of fructification, whose connection 
with the stalk is then destroyed. The spikes are at first en- 
veloped in a mucous membrane, and are composed of two 
sorts of bodies closely packed together, and considered by 
M. Dunal to be ovules and anthers. These bodies are some- 
times intermixed, sometimes stationed separately from each 
other. The so called ovules are little white semitransparent 
bodies, surrounded by a sort of projecting hood, beyond wdiich 
a narrow papilla projects : this papilla is always turned 
towards the anthers. The latter are little flat parallelopi- 
pedons, rounded at the two ends ; they consist of a mem- 
branous sac of great tenuity, in which are found numerous 
grains of spherical or elliptical pollen. (Ann. Sc., n. s. vii. 227. 
t. 12, 13.) M. Fabre is represented as having proved experi- 
mentally that the latter impregnate the former; and he has 
traced the ovules from their first impregnation to their com- 
pletion, and seen and described their germination. (Id. ix. 
115. t. 13.) It appears that no trace of embryo is discoverable 
in the ripe seed. 
In the second section of this order, to which the name 
Salvinieae may be given, and which consists of the genera 
Salvinia and Azolla, we find at the base of the leaves mem- 
branaceous involucres of two sorts, and containing different 
organs. One kind includes a bunch of cases (sporangia, 
Martins), containing only one grain in Salvinia, and from six 
to nine in Azolla. The integument of these cases is thin, 
reticulated, brownish, and does not swell in water like that of 
true Marsileaceae ; the pedicle which supports them appears, 
