176  A  Study  of  Starch  Grains.  {Am'S;?m™* 
itself  is  changed  into  starch.  Another  view  is  that  the  protoplasm 
is  changed  into  starch.  In  opposition  to  these  chemical  theories  we 
find  also  physical  theories.  These  are  based  upon  the  difference  in 
the  character  and  action  ot  the  rays  of  the  sun,  which  are  absorbed 
by  the  chlorophyll,  and  those  that  pass  through  it.  These  results 
have  been  obtained  by  the  examination  of  solutions  of  chlorophyll 
by  means  of  the  spectroscope.  One  view,  which  is  supported  by 
Lommel  and  Miiller,  and  apparently  confirmed  by  the  observations 
of  other  investigators,  is  that  the  rays — more  especially  the  blue  and 
red — which  are  absorbed  by  the  chlorophyll  are  changed  into  some 
other  form  of  energy,  which  is  able  to  make  starch  synthetically  out 
of  carbon  dioxide  and  water.  Pringsheim,  on  the  other  hand,  con- 
siders that  the  chlorophyll  acts  as  a  filter  of  the  rays  of  light,  and 
that  those  absorbed  are  not  active  in  the  work  of  assimilation,  but 
on  the  contrary  interfere  with  the  process,  so  that  those  that 
pass  through  are  the  rays  which  effect  the  production  of  starch.  It 
is  also  held  that  just  as  there  is  a  combination  in  the  blood  between- 
haemoglobin  and  oxygen,  so  the  chlorophyll  combines  and  fixes 
carbon  dioxide.  It  is  difficult  to  decide  just  what  is  the  process  in 
the  manufacture  of  starch  by  the  plant,  and  it  is  not  unlikely  that  the 
rays  absorbed  by  the  chlorophyll  are  those  directly  concerned  in  the 
process,  as  a  number  of  investigators  have  found  that  the  produc- 
tion of  starch  is  much  more  energetic  in  green  plants  when  exposed 
to  those  colors  which  are  absorbed  by  the  chlorophyll  solution  to 
the  greatest  extent.  And  yet  who  can  say  that  the  secret  of  life 
does  not  lie  here  in  the  chloroplastid,  that  it  is  not  only  the  mill 
which  supplies  the  world  with  its  food,  but  it  is  also  the  organ  which 
changes  the  energy  of  the  sun  into  vital  energy.  It  may  be  that  the 
sun  is  the  source  of  the  energy,  the  carbon  dioxide  and  water  the  ma- 
terials, and  the  chloroplastid  the  laboratory  whereby  vital  energy 
is  created  and  bound  and  held  in  the  substance  which  we  call  starch. 
If  we  stop  a  moment  to  consider  this  we  will  find  that  the  animal 
creation  is  wholly  dependent  for  its  energy  upon  the  starch  grain 
produced  in  the  plant.  If  the  plant  (as  clover),  or  seed,  or  fruit 
(as  oats,  etc.),  is  consumed  by  horses,  the  energy  of  the  starch  grain 
is  changed  to  horse-power.  If  the  plant  is  consumed  by  cows  it  be- 
comes milk  and  meat,  and  may  in  turn  furnish  us  energy.  From  these 
products  of  the  animal  creation  as  well  as  from  the  plants  directly,, 
we  obtain  our  power  to  live  and  act,  u  e.,  the  energy  we  possess 
