402 
Insects  and  Flowers. 
Am.  Jour.  Pharm. 
Aug.,  1886. 
One  of  our  recent  poetic  botanists  asserts  that,  as  the  bee  flowers 
grew  bluer,  the  bees,  must  have  grown  fonder  and  fonder  of  blue, 
and,  as  they  grew  fonder  of  blue,  they  must  have  more  and  more 
constantly  preferred  the  bluest  flowers. 
Thus  the  special  tastes  of  insects  are  supposed  to  be  the  selective 
agency  for  developing,  white,  pink,  red,  purple,  and  blue  petals  from 
the  original  yellow  ones.  But,  we  cannot  help  asking  how  could 
insects  exercise  any  selective  agency  unless  the  petals  had  first  shown 
any  tendency  to  vary?  We  find  no  satisfactory  answer  to  this  ques- 
tion; but  we  have  the  following  facts  before  us,  which  speak  for 
themselves : 
The  pigments  of  colored  petals  are  stored  in  the  ordinary  tissues 
of  the  plant,  and  a  very  small  number  is  required  to  produce  a  seem- 
ingly endless  variety. 
The  colored  substances  are  in  many  cases  the  same  as  those  left  in 
the  foliage  from  which  chlorophyll  has  disappeared;  so  that  bright 
petals  are  often  exactly  like  leaves  which  have  turned  yellow  and 
red  in  autumn,  or  the  very  red  and  yellow  leaves  of  early  spring. 
White,  which  is  the  dress  of  so  many  flowers,  is  due  simply 
to  the  reflection  of  light  through  colorless  air-filled  cells  and 
tissues. 
Black  spots  on  flower  or  seeds,  as,  for  example,  on  the  garden 
bean,  owe  their  origin  merely  to  a  concentration  of  dense  violet  pig- 
ment; and  the  blackness  of  so  many  berries  is  produced  in  the  same 
way,  by  violet  thickly  heaped  on  in  patches,  which  become,  there- 
fore, impenetrable  to  light.  The  apparently  black  berries  of  deadly 
nightshade  contain  a  splendid  violet,  easily  soluble  in  water  and 
alcohol;  with  acid  it  becomes  a  purplish-red,  and  with  ammonia, 
green.  Setting  aside  chlorophyll  green,  which  is  only  exceptionally  a 
flower  color,  the  remaining  pigments  are  yellow,  red,  and  blue;  the 
two  latter  exist  in  the  cell  sap.  Yellow  is  identical  with  the  sub- 
stance which,  in  the  animal  kingdom,  goes  under  the  name  of  lipo- 
chrome;  and  the  color  of  the  rind  of  an  orange  is  due  to  the  same 
pigment  as  is  found  in  the  yellow  of  the  buttercup.  It  is  only  a 
denser  deposit  of  it.  The  red  of  roses,  pinks,  and  poppies,  is  due  to 
a  single  pigment;  it  is  just  a  matter  of  difference  in  intensity.  It 
may  be  affected  by  the  presence  of  an  acid  in  the  cells,  and,  some- 
times, by  the  addition  of  a  small  quantity  of  lipochrome;  not  that  a 
mixture  of  the  two  colors  takes  place  in  the  cells,  but  that  rose-red 
