AmtimeriMiarm" }       Modification  of  Color  in  Plants.  4T7 
demonstrated.  On  the  other  hand,  such  studies  are  quite  difficult, 
and  usually  will  involve  considerable  expense,  as  large  quantities  of 
material  are  necessary  in  order  to  obtain  a  given  constituent.  It  is 
my  object  in  this  paper. to  report  on  some  experiments  which  I  con- 
ducted nearly  ten  years  ago  with  a  view  of  modifying  color  in 
flowers.  These  studies  have  not  been  previously  reported  upon, 
because  the  results  at  that  time  did  not  seem  to  be  sufficiently  strongly 
marked,  and  unless  the  paper  was  illustrated  with  colored  plates,  no 
adequate  idea  of  these  changes  could  be  seen.  Fortunately  all  of 
the  work  which  I  did  at  that  time  is  conserved  either  with  colored 
photographs  or  with  drawings  in  which  the  shades  of  color  were 
quite  accurate.  Upon  resuming  my  work  in  the  study  of  color  in 
flowers  I  have,  become  impressed  with  the  fact  that  this  earlier 
work  was  really  more  valuable  than  I  thought  at  the  time. 
Studies  of  changes  of  the  color  in  flowers,  the  plant  being  in  a 
fixed  environment  is  essentially  a  physiological  study  of  the  plant 
soil. 
Upon  the  sea  coast  the  flowers  of  the  Hydrangea  Otaksa  invari- 
ably become  blue  in  the  second  year- even  though  the  flowers  in  the 
plants  were  pink  or  a  strong  reddish  color.  This  is  usually  attributed 
to  the  salt  air,  the  fine  spray  of  sodium  chloride  having  an  influence 
on  the  color  change.  The  older,  weakly  woody  plants  of  Hydrangea 
Otaksa  almost  invariably  have  a  tendency  to  produce  blue  flowers, 
although  in  many  environments  the  plants  will  run  into  foliage  and 
not  produce  any  flowers  at  all.  It  is  a  very  common  belief  that  the 
flowers  of  hydrangea  may  be  changed  by  the  introduction  of  chem- 
icals into  the  soil.  In  fact,  very  many  gardeners  who  are  anxious 
to  have  blue  flowering  hydrangea  plants  at  Easter  time,  invariably 
add  a  piece  of  alum  about  the  size  of  a  walnut  to  the  soil  of  the  pots 
during  the  summer.  The  study  of  the  pigment  cells  of  any  portion 
of  the  plant  shows  that  the  change  of  color  would  be  produced  by 
a  great  variety  or  reagents.  It  is  quite  well  known  that  the  sub- 
stances of  the  soil  may  be  changed  by  the  introduction  of  chemicals 
or  other  soils.  These  produce  changes  in  the  plant  cell.  The  carbo- 
hydrates for  instance  in  a  green  algae  may  be  changed  into  reserve 
starch  by  adding  calcium  nitrate  to  the  water  surrounding  them.  In 
the  same  way  a  reserve  starch  will  be  duplicated  in  the  cells  of 
foliage  leaves  when  they  are  attacked  by  certain  fungi. 
