180 PRINCIPLES OF BOTANY, ETC. 
ceptacle, to consider it as another style below the 
germen; and he accordingly reduces various ge- 
nera of this kind to his class Gynandria, (§ 142). 
Sivas 
The situation of the germen is an excellent generic 
character. 
However similarly constructed plants may be, if 
the germen in one is above and in another is below 
the calyx, they must form separate genera. There 
is no instance known where this situation of the ger- 
men is subject to variation. A single exception is 
found in the genus Saxifraga; where in some spe- 
cies the germen is under the calyx; in some it is 
half above and half below, and in others it is wholly 
above the calyx. But here we see the transition 
distinctly, and consequently this instance alone is 
az exception to the rule. 
§ 172. 
The situation or rather the insertion of the stamina 
as of great importance in a generic character. 
Whether the stamina are inserted in the calyx, 
in the corolla, or in the receptacle, they afford a 
principal character in establishing genera. Let the 
conformity of the whole plant or flower be what it 
may, the genera must be determined by the inser- 
tion of the stamina. In the caryophyllous plants, 
particularly in Lychnis and Silene, some filaments 
are inserted in the receptacle, and some in the co- 
rolla: these accordingly make one exception to the 
rule. 
§ 173. 
