AmMay^ro:frn1'}      The  Structure  of  the  Starch  Grain.  225 
parts  of  the  grain  more  than  others,  and  in  another  place  he  states 
that  "  die  Lamellen  die  im  frischen  Starkekorn  als  dunklere  Linien 
erscheinen,  sind  diejenigen  welche  den  Farbstoff  am  reichlichsten 
einsaugen."  In  speaking  of  Meyer's  work  he  goes  on  to  say : 
"  Meyer  erwahnt,  dass  bei  der  Farbung  mit  Methylviolet  der 
Farbstoff  besonders  von  den  weicheren  Lamellen  beibehalten  wird." 
The  only  unfortunate  thing  is  that  we  do  not  know  to  what  layers 
these  authors  refer  when  they  speak  of  "  weicheren  Lamellen  "  and 
lamellae  with  "  dunklere  Linien."  There  seems  to  be  no  doubt, 
however,  that  what  they  have  in  mind  corresponds  to  my  own 
observations,  that  is,  it  is  the  layers  which  are  colloidal  in  character 
which  take  up  the  stains  ;  in  other  words,  the  point  of  origin  of 
growth  and  the  layers  alternating  with  it. 
Another  interesting  feature  serving  to  differentiate  the  layers  of 
the  starch  grain  is  the  behavior  toward  dilute  iodine  solutions. 
The  layers  which  are  not  affected  by  the  aniline  stains  become  blue 
with  iodine,  the  alternate  layers  and  the  point  of  origin  of  growth 
remaining  unaffected.  The  layers  thus  affected  by  iodine  are  the 
ones  which  are  rich  in  granulose  and  are  more  clearly  denned  in 
the  grains  of  potato  and  wheat  starch  than  in  corn  starch.  These 
layers  become  crystalloidal  in  character  on  treatment  with  water 
at  60  0  or  65 0  C.  for  about  an  hour,  and  also  with  chromic  acid, 
calcium  nitrate,  saliva,  and  other  reagents.1 
The  behavior  of  potato  starch  toward  these  reagents  may  be 
briefly  summarized  as  follows  (Jigs.  1-10)  :  The  first  effect  of  the 
reagent  is  to  make  the  lamellae  more  distinct  (Jigs.  1-2) ;  this  is 
followed  by  the  development  of  the  crystalloidal  character  of  the 
lamellae  {fig.  j),  which  is  most  pronounced  in  those  colored  blue 
with  iodine  ;  this  is  followed  by  the  production  of  small  clefts  or 
channels  (fig.  connecting  the  contiguous  lamellae,  particularly  in 
the  middle  of  the  grain  ;  succeeding  this  there  is  the  formation  of 
channels  which  are  larger  and  plume-like  in  appearance  (Jig.  5),  the 
grain  meanwhile  swelling  quite  perceptibly,  the  middle  portion 
becoming  clearer  and  assuming  a  zigzag  outline  (Jig.  6),  between 
which  and  the  periphery  of  the  grain  a  number  of  crystalloidal 
lamellae  arise  (fig.  7) ;  the  grain  now  becomes  spherical  and  marked 
by  a  number  of  concentric  lamellae  near  the  periphery  ;  the  latter 
1  Proc.  Acad.  Nat.  Sci.  Philadelphia  53  :    450,  1901. 
