Am.  Jour.  Pharm. 
April,  1899. 
A  Study  of  Starch  Grains. 
m 
comes  to  us  and  every  animal  from  a  kind  of  potential  (probably 
vital)  energy  stored  in  the  plant,  which  the  latter  has  received 
from  the  kinetic  energy  of  the  sun.  The  value  of  one  food  over 
another  lies  in  the  amount  of  stored  energy  that  it  contains,  and 
which  is  ordinarily  calculated  as  fuel  value.  From  the  considera- 
tion of  the  plant  along  these  lines,  some  have  defined  the  plant  as  a 
machine  for  storing  energy. 
KINDS  OF  STARCH. 
It  was  stated  that  if  we  examine  the  chloroplastid  at  the  close 
of  a  day  in  summer,  when  the  sun  has  been  shining  brightly  upon 
the  plant,  we  would  observe,  by  proper  manipulation,  minute  starch 
grains,  called  assimilation  starch,  in  each  chloroplastid.  If  the  lat- 
ter is  examined  in  the  early  morning,  it  will  be  found  to  be 
comparatively  free  from  starch ;  and  the  question  arises,  what  has 
become  of  it  ?  We  find  that  during  the  night  it  has  been  changed 
into  soluble  carbohydrates  by  the  aid  of  ferments  and  other  sub- 
stances, and,  as  such,  transported  to  the  portions  of  the  plant  that 
require  food.  If  this  process  takes  place  during  activity  of  growth 
in  the  plant,  it  is  transmitted  to  the  growing  point  of  root,  stem  or 
leaf,  etc.,  and  is  utilized  in  the  building-up  of  new  cells,  etc.  In 
many  of  the  cells  through  which  the  solution  of  carbohydrates 
passes  en  route  to  the  growing  point,  or  even  at  the  growing  point, 
it  may  be  transformed  back  to  starch  by  a  colorless  chloroplastid, 
called  leucoplastid.  Starch  that  is  produced  in  this  manner,  and 
being  in  a  transition  or  resting  stage,  awaiting  further  orders  or 
calls,  so  to  speak,  before  going  further,  is  spoken  of  as  transitory 
starch.  The  starch  in  the  medullary  rays,  as  well  as  in  other  cells  of 
the  wood  and  bark  of  plants,  is  of  this  character,  and  distinguished 
by  being  in  the  form  of  rather  small  and  nearly  spherical  grains. 
After  the  production  of  the  elements  (as  roots,  branches  with 
leaves,  flowers,  etc.)  required  for  one  year's  growth,  most  plants,  as 
a  rule,  provide  food  for  their  next  year's  growth,  if  they  survive,  or 
for  that  of  their  offspring.  The  character  of  the  provisions  laid  by 
depends  upon  the  nature  of  the  plant  and  the  conditions  under  which 
it  develops.  While  starch  is  commonly  the  principle  stored  for  this 
purpose,  in  some  cases  other  substances  represent  the  reserve  pro- 
duct, as  cellulose  (in  nux  vomica),  oil  and  proteids  (in  mustard), 
etc.    Oil  replaces  starch  in  seeds  which  are  to  be  transported  to 
