Fructification of the submersed Algce. 503 
substance, compared by Bernard de Jussieu to dissolved 
gum. The original state in which it is found in every flower, 
before the act of fecundation, is that of a mucus, but it is per- 
fectly active even in that state, since its particles, after becom- 
ing a little dry, if put into certain fluids, are seen, by the help 
of the microscope, acting in the same manner as when in the 
state of perfect farina. 
The plants whose fructification lies unsheltered under water 
are very few in number ; and such of them as have been hitherto 
thoroughly examined, (the Ceratophyllum and the Chara), 
have antherge furnished with mucous pollen, not bursting in 
the fecundation. From the time of Dillenius it has been ob- 
served, that the submersed antherge of the Ceratophyllum never 
burst, but are found whole, though the seeds be ripe.* If 
squeezed, they shed a soft and pulpous matter, like that which 
is found in unripe antherae. Dillenius suspected that the 
fructification of the Chara being equally submersed, its antherae 
and pollen would be of the same nature with the preceding, 
and observations have fully confirmed the conjectures of this 
great naturalist. The antherae of the Chara do not burst in 
fecundation ; its pollen is mucous ; the germen has no pistil- 
lum, and is probably fecundated through its receptaculum, as 
there exists in each internodium, according to modern obser- 
vations, -f a chain of vessels which twist round the antherae and 
the fruit, and in which a circulation of humours is visible, at 
least in the period of fructification. 
If pollen therefore, under the shape of farina, be unfit for 
fecundation in the water ; if nature has taken a particular care 
to guard this operation from the presence of that element ; if 
* Plantce Gissenses, pag. 91. f Corti, Osserv. Microscop. Lucca, 1774. 
MDCCXCVI. 3 T 
