With regard to the bony skeleton, lateral curvature of the spine is,
in mild manifestation, very frequent, and is too common even in the
higher degrees. The chief causes of this deformity are:

(1) The natural softness and want of stability in the rapidly growing
bones and muscles;

(2) The rapid development of the bust, which throws a constantly
increasing burden on these weakened muscles and bones; and

(3) The general lassitude noticeable amongst girls at this time which
makes them yield to the temptation to stand on one leg, to cross one
leg over the other, and to write or read leaning on one elbow and
bending over the table, whereas they ought to be sitting upright.
Unless constant vigilance is exerted, deformity is pretty sure to
occur--a deformity which always has a bad influence over the girl's
health and strength, and which, in those cases where it is complicated
by the pathological softness of bones found in cases of rickets, may
cause serious alteration in shape and interfere with the functions of
the pelvis in later life.

2. Changes in the Mental Nature.--These are at least as remarkable
as the changes in the bodily framework. There is a slight diminution
in the power of memorising, but the faculties of attention, of
reasoning, and of imagination, develop rapidly. Probably the power of
appreciation of the beautiful appears about this time, a faculty which
is usually dormant during childhood. More especially is this true with
regard to the beauty of landscape; the child seldom enjoys a landscape
as such, although isolated beauties, such as that of flowers, may
sometimes be appreciated.