218 
The  Structure  of  the  Starch  Grain. 
Am.  Jour.  Pharm. 
May,  1907. 
idea  that  growth  took  place  from  the  outside,  that  through  one  or 
more  funnel-like  openings  at  the  periphery  of  the  grain  new  sub- 
stances entered  and  new  layers  were  formed  therefrom,  the  outer 
layers  thus  being  the  oldest,  in  contradistinction  to  the  view  advanced 
by  Fritsche.  (4)  Then  followed  a  series  of  contributions  in  which 
the  growth  of  the  starch  grain  was  likened  to  that  of  the  cell  wall 
and  the  formation  of  cells.  This  theory,  with  certain  modifications, 
was  advocated  by  Miinster  (10),  Walpers  (11),  Reissek  (12),  C.  Na- 
geli  (13),  Kutzing  (14),  and  Hartig  (15).  (5)  While  Nageli  (16) 
recognized  that  assimilation  starch  arose  in  plastids,  he  considered 
that  most  starch  grains  arose  free  in  the  cell  sap  under  the  influence 
of  living  protoplasm,  and  it  was  not  until  1880  that  Schimper  (17) 
demonstrated  that  all  starch  grains  develop  within  plastids  and  that 
in  the  case  of  reserve  starch  grains  the  leucoplastids  finally 
disappear.  Schimper  further  showed  that  the  outer  portion  of  the 
grain  is  the  youngest,  and  thus  substantiated  the  view  of  Fritsche 
concerning  its  development. 
If  we  consult  any  of  the  standard  works  on  organic  chemistry, 
we  find  that  the  formula  which  is  generally  accepted  for  starch  is 
n  (C6H10O5),  this  being  the  formula  recognized  by  Pfeffer,  Tollens, 
and  Mylius.  It  is  supposed  that  the  molecular  composition  is  quite 
complex,  the  grain  being  composed  of  different  single  groups  of 
C6H10O5  or  multiples  of  the  same.  While  this  formula  may  be 
accepted  in  a  general  way,  still  it  has  been  shown  that  there  are  at 
least  two  substances  which  enter  into  the  composition  of  the  starch 
grain.  Nageli  (16)  has  shown  that  the  starch  grain  consists  of  two 
different  substances,  one  which  is  soluble  in  ferments,  and  called  by 
him  granulose,  and  another  which  is  insoluble  in  saliva,  and  called 
by  him  starch  cellulose.  He  showed  that  when  the  starch  grain 
was  deprived  of  its  water  the  lamellae  were  not  apparent,  and  there- 
fore he  concluded  that  the  layering  was  due  to  a  difference  in  the 
amount  of  water  present  in  the  different  lamellae.  This  view  has 
given  rise  to  the  formula  suggested  by  W.  Nageli  (18)  for  the  starch 
grain,  which  is  6C6H10O5  +  H20,  or  C36H62031.  Maschke  (25)  con- 
sidered that  the  starch  grain  consisted  of  alternate  layers  of  cellu- 
lose between  which  starch  substance  was  deposited  in  two  modifica- 
tions, one  soluble  in  water  forming  the  light-colored  lamellae,  and 
another  insoluble  in  water  forming  the  dark  layers.  This  view  was 
not  adopted,  however,  and  Nageli's  theory  prevailed  until  1886, 
