Am,AJp°rUii;imrm'}         A  Study  of  Starch  Grains.  181 
which  he  considers  it  to  be  made  up  of  (i)  a-amylose  ;  (2)  /3-amy- 
lose,  and  (3)  amylodextrin,  a  decomposition  product  of  amylose. 
He  also  believes  that  inasmuch  as  there  is  an  anhydride  of 
dextrose  which  does  not  readily  take  up  water  there  is  probably 
also  an  anhydride  of  amylose  which  even  on  boiling  with  water 
is  hydrated  with  difficulty,  and  this  is  the  substance  that  has  given 
rise  to  the  hypothesis  that  there  is  present  a  starch  cellulose.  This 
latter  term  has  been  used  for  a  number  of  different  substances :  (1) 
Mixtures  of  amylodextrin  and  a-amylose ;  (2)  solutions  of  a-amy- 
lose and  /9-amylose ;  (3)  solutions  of  /9-amylose  with  various  sub- 
stances as  nitrogen-holding  substances,  impure  fatty  products,  pure 
amylodextrin,  and  the  walls  of  plant  cells  which  are  contained  in 
commercial  starches  unless  carefully  purified.  He  obtained  the  a- 
amylose  upon  treating  starch  paste  (Starkekleister)  with  malt  solu- 
tions (Malzauszug)  and  by  the  action  of  hot  dilute  solutions  of  hydro- 
chloric acid  upon  the  whole  starch  grain.  The  portion  (^-amylose) 
remaining  is  distinguished  from  the  portion  dissolved,  in  that  it  is 
not  soluble  in  water  and  becomes  slightly  reddish  in  color,  and  not 
blue  with  iodine  solutions. 
He  considers  the  starch  grain  to  be  made  up  of  two  kinds  of 
acicular  crystals  (which  he  calls  "  Trichiten  "),  viz.;  a-amylose  and 
j3-amylose,  and  that  in  certain  starch  grains  which  are  colored  red 
with  iodine  and  not  blue,  there  is  also  present  amylodextrin 
and  dextrin.  He  further  says  that  most  starch  grains  consist 
altogether  or  nearly  so,  of  amylose,  and  that  such  are  colored  pure 
blue  with  iodine.  These  latter  starch  grains  are  made  up  of  sphere- 
crystals  of  amylose,  arranged  in  layers,  and  these  layers  may 
consist  of  crystals  of  either  a-amylose  or  ^-amylose,  or  both,  and 
that  some  starch  grains  contain  in  addition  large  amounts  of  amylo- 
dextrin and  dextrin,  as  in  Iris  germanica,  Gentiana  lutea,  Oryza  sativay 
some  orchids,  grasses,  etc. 
MICRO-PHYSICAL  EXAMINATION  OF  STARCH  GRAINS. 
Starch  grains  generally  occur  in  isolated  grains.  Not  infrequently, 
however,  they  are  found  in  groups  of  2  to  4  grains,  when  they  are 
distinguished  as  2-,  3-  or  4-compound.  In  rice  they  are  from  4-  to 
100-,  in  oats  as  many  as  300  and  in  spinach  as  numerous  as  30,000- 
compound.  The  individuals  of  compound  grains  are  in  some  cases 
easily  separated  from  each  other.    This  separation  of  the  grains 
