165 
Dr Fleming on a remarkable Species of Trichia. 
throw of all the modifications of this theory, leaves the inquirer 
still in the dark respecting the origin of the fungi which appear 
in new soils and situations. 
The microscope, though an instrument of philosophical inves- 
tigation fruitful of error, has been singularly useful to the bo- 
tanist, by enabling him to investigate with success the repro- 
ductive organs of plants. He has been able, by the help which 
it affords, to determine the true forms of many seeds, which are 
too small to be visible to the naked eye, and to develope the 
structure of the minute organs in which these are prepared, 
when the ordinary methods of observation could not be em- 
ployed. These objects, in spite of many difficulties, have been 
accomplished in reference to the fungi, the situation of their or- 
gans of fructification has been determined, and the existence of 
their numerous, though minute, seeds demonstrated. So mi- 
nute, indeed, are these seeds now known to be, that they are ca- 
pable of gaining admittance into the smallest crevice ; and so 
light, as to be easily carried about in the air. These circum- 
stances sufficiently explain the universality of their occurrence, 
and lead us to suspect their presence, not merely in the earth, 
the waters, and the air, but even in the living textures of orga- 
nised beings. They are ready, when favourable combinations 
occur, to expand into the forms of maturity. But while the 
lightness, the smallness, and, we may add, the vivaciousness of 
the seeds of the fungi, account for their presence in almost eve- 
ry situation, the mind is naturally led to reflect on the infinite 
number of these germs, at present dormant, within us, and 
around us, which, in the absence of favourable circumstances, 
may never be permitted to vegetate. And, considering the con- 
tingency of their evolution, botanists may expect the appearance 
of new species in situations, where their occurrence had not hi- 
therto been detected, and, where it might even have been suppo- 
sed, that their germination could not have taken place 
These remarks have occurred, upon contemplating the pecu- 
liar circumstances in which the plant we are now to describe 
made its appearance, — in the phial of a laboratory, and in the 
midst of a solution of a neutral salt ! 
In the spring of the year 1818, I had occasion to prepare a 
neutral succinate of ammonia, by adding to a saturated solution 
