f246 M. Vaucher on the Ckcimgne iyf^ tJio Lake of Geneva. 
Tlie true seed of this plant, at the moment of its develope- 
merit, occupies almost the entire capacity of the sac that con- 
tains it, through which it pushes forth its first filament; When 
this filament has reached a certain size, it begins to form its first 
verticil, which comes forth a little below the summit, exhibiting . 
at first only one ray, afterwards two, and then three or more. 
In proportion as the filament elongates, we observe swellings 
to form below the first verticil, which give birth to simple ra- 
dicles. These radicles prolong themselves, and serve to fix and 
perhaps nourish the plant. The seed remains long attached to 
the' stem, so that the organs of the future fructification may be 
seen distinctly before the seed has finally separated. These se- 
veral points in the fructification and germination of this plant, 
M. Vauclier has illustrated by suitable descriptive drawings. 
This plant possesses some interest in a geological view. M. 
Leman is said by our authotv to have proved, in a paper 
in the Journal des Mines, 1812, p. 341, that the small fossil, 
designated under the name Gyrogoiiite.^ and found in fresh wa- 
ter formations, is a petrifaction of different species of this aquatic 
plant. In truth, as he observes, the resemblance between the 
gyrogonke and the fr-iiit of the charagne, is perfect. In farther 
proof of this opinion, Mr V,aucher remarks, that the exterior 
envelope before described, which at first is mucilaginous, be- 
comes afterwards as hard as porcelain, so as to resist strongly 
any attempt to break it : and, in examining the bottoms of 
ditches, he has found great quantities of the seeds of these plants 
of great whiteness, and in perfect preservation. Such of these 
seeds as are too deeply buried to germinate, preserve themselves 
for a long time in this state ; but at length they become pene- 
trated by earthy matter, and formed into petrifactions. It 
would be interesting to ascertain if the substance of the gyrogo- 
nites be very different from that of the seeds of these plants. 
Our gyrogonites, adds M. Vaucher, are larger than the seeds of 
the common plant : but we also find gyrogonites much smaller ; 
and there exist, moreover, some species of this genus, among 
others, that of our lake, Cliara tomentosa^ whose seeds are incom- 
parably more large than those which form the subject of this 
memoir. 
