16 
scales which preceded them ; the whole presenting 
a striking example of the way in which, in a com¬ 
plicated structure, the principles of equipoise and 
symmetry are maintained. Were it possible to weigh 
the corresponding parts we should, no doubt, find 
their weights the same as well as their magnitude 
and form. The numerical proportions of such a 
flower are (5 x 5) + 5 + (5 x 2) + (5 x 2). 
32. The red Brugmansia offers an instance of a 
more simple arrangement. In this flower we do not 
at first perceive any symmetry except that the end 
of the long tubular corolla is divided into five equal 
lobes, which, if they had been formed by rule and 
compass, could not be more exactly alike. On 
the outside of this corolla, upon each of its five lobes 
are three ribs, in all fifteen, or 5 x 3 ; and this plant 
never produces any other number. Upon opening 
it we find the same number, five, still prevalent in 
the stamens; and the external cup or calyx is also 
in reality divided into five triangular teeth, although, 
owing to the way in which the teeth adhere, this is 
not at first sight apparent. The fundamental num¬ 
ber still being five, this structure is represented by 
5 +(5 x3) + 5. 
33. All these remarkable examples of floral sym¬ 
metry seem to show that there is a centrifugal force 
operating in the formation of flowers, which, being 
equal in all dii'ections, can scarcely fail to produce 
such a result. 
34. In the ripe fruit of the apple, no symmetrical 
arrangement of parts is at first apparent; but it once 
had a perfectly regular structure, in which all the 
parts were exactly balanced, and even when ripe 
its symmetry is visible to the eye of intelligence. 
