512 PRINCIPLES OF BOTANY, ETC. 
A inore important question, what constitutes the 
impregnating power of the pollen, or on what does 
it depend? remains still unanswered. Is it a subtile 
oily vapour, or a subtile volatile aura? or is it, 
according to others, electricity, or any other power? 
Stil we are here in the dark*. 
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The female organs of fructification are the pistil, 
(§ 91-94), which consists of the germen, the style, 
and the stigma. The germen varies in its shape 
and structure in various plants. It is composed of 
all those vessels which we noticed in the rest of the 
plant, their direction and distribution only differing 
in each. ‘The seeds, if the germen itself does not 
become a seed, lie in it, and are connected with it 
by the navel-string, (§ 114). In its interior it con- 
tains aclear fluid, in which nothing particular can 
be found. When the germen itself becomes the seed, 
the navel-string is very short. ‘The internal struc- 
ture of such a germen is the same, as that of the 
seed lying in it. 
* This leads me to mention a remarkable electrical pheno- 
menon, in some deep red, or orange- -yellow tinged flowers, 
which Linné’s daughter first discovered. She repeatedly ob- 
served, in a dark evening, the atmosphere being calm and 
warm, a sparkling round the flowers of the Tropeolum majus. 
The same was afterwards observed by others in other plants. 
The Dictamnus a/bus affords another phenomenon. The very 
volatile fine oil, which in hot weather exudes from its flowers, 
gan be kindled by a candle, and gives out a light blue flame. 
The 
