ed at the knee,
and the body is stooping forward. While standing in this position, the
muscles of the lower limbs and back are in continued tension, which
exhausts and weakens them.]

-=-=-=-=-=-=-=-=-=-=-=-=

What is represented by figs. 48 and 49?

-=-=-=-=-=-=-=-=-=-=-=-=

200. When it is necessary to call into action a part of the muscles of
the system in the performance of any duty, as those of the lower limbs
in walking, if the muscles of other parts are in a state of inaction,
the influence of the nervous system can be determined in an undivided
manner upon those parts of the lower limbs in action; hence they will
not so soon become wearied or exhausted, as when this influence is
divided between a greater number of muscles. In performing any labor,
as in speaking, reading, singing, mowing, sewing, &c., there will be
less exhaustion, and the effort can be longer maintained in the erect
position of the body and head, than in a stooping attitude.

_Experiment._ Hold in each hand a pail of water or equal weights, in a
stooping posture, as long as it can be done without much suffering and
injury. Again, when the muscular pain has ceased, hold the same pails
of water, for the same length of time, in an erect posture, and note
the difference in the fatigue of the muscles.

201. If the stooping posture is acquired in youth, we are quite
certain of seeing the deformed shoulders in old age. Hence the
importance of duly exercising the muscles of the back, for when they
are properly developed, the child can and will stand erect. In this
attitude, the shoulders will be thrown back, and the chest will become
broad and full.

202. Pupils, while standing during recitations, often inadvertently
assume the attitude represented by fig. 49, and it is the duty of
teachers to correct this position when assumed. When a child or adult
has contracted a habit of stooping, and has become round-shouldered,
it can be measurably, and generally, wholly, remedied by moderate and
repeated efforts to bring the shoulders back, and the spinal column in
an erect position. This deformity can and should be remedied in our
schools. It may take months to accomplish the desired end, yet it can
be done as well under the direction of the kind instructor, as under
the stern, military drill sergeant, who never fails to correct this
deformity among his raw recruits.

-=-=-=-=-=-=-=-=-=-=-=-=

200. What suggestion when it is necessary to call