Since  the  accumulation  of  the  superfluous
carbon  supplied  by  the  food  gives  rise  to
morbid  and  diseased  states  of  the  body,'  we
shall  now  be  enabled  to  understand  why  defi-
cient exercise  should  he  a  source  of  physical
ill-being,  and  why,  on  the  contrary,  the  proper
u^e  of  the  muscles  should  be  so  essential  a  con-
dition for  the  maintenance  of  health,  since  it
is  in  them  that  the  great  formation  of  tin-
eliminated  carbon  is  effected.  \Vc  shall  also
not  fail  to  see  why,  since  during  exercise  the
excretion  of  water  is  so  largely  incronscd,  the
blood  necessarily  becomes  less  diluted  and
richer  in  quantity.
Whilst  insufficiency  of  exercise  gives  rise  to
a  weak  action  of  the  heart,  and  very  frequently
to  fatty  degeneration  of  that  organ,  exercise
that  is  not  excessive,  although  it  increases  the
beats  of  the  heart  from  ten  to  thirty  beyond
this  acceleration,  and  imparting  greater  force
to  the  pulsations,  does  not  interfere  with  their
regularity.  Furthermore,  muscular  exercise,
by  considerably  augmenting  the  flow  of  the
blood  through  the  whole  body,  the  heart  in-
cluded, exercises  a  most  beneficial  function,
"  since  it  causes  in  all  organs  a  more  rapid
outflow  of  plasma  and  absorption — in  other
words,  a  quicker  renewal.  In  this  way  also
it  removes  the  products  of  their  action,  which
accumulate  in  organs,  and  restores  the  power
of  action  to  various  parts  of  the  body."^

Palpitation,  enlargement,  and  valvular  dis-
ease of  the  heart  result  from  excessive  or
injudicious  exercise.  Wherever,  therefore,
fatigue  or  embarris'^ment  of  the  heart  shows
itself  rest  must  be  had  recourse  to.  Persons
having  weak  hearts  suffer  greatly  in  ascending
mountain  or  other  heights.
