1 86  Aril  of  Celastrus  Scandens.  {AmAJ£ff;£l£rD1" 
same  change  of  color  was  effected  when  concentrated  sulphuric  acid 
was  added  to  the  chloroform  solution.  With  iodine  solution  in 
potassium  iodide  the  chromatophores  turn  blue-green,  like  the  color 
characteristic  of  the  Cyanophyceae.  According  to  Zimmerman,6 
carotin  thus  treated  yields  a  greenish  or  greenish-yellow  color,  and 
with  concentrated  sulphuric  acid,  first  violet  and  then  indigo-blue. 
There  is  certainly  much  resemblance  also  between  the  effect  of 
iodine  and  concentrated  sulphuric  acid  upon  carotin  and  upon  the 
red  pigment  of  Celastrus  scandens. 
Lacking,  however,  complete  correspondence,  I  next  determined 
to  discover  if  it  approached  xanthin  more  closely  in  its  properties. 
It  differs  from  this  in  its  most  conspicuous,  although  on  that 
account  by  no  means  most  important  property,  and  that  is  its  color. 
Xanthin,  as  described  by  Zimmerman,7  occurs  in  yellow  chromo- 
plasts  in  amorphous  form,  and  especially  in  small  granules.  Its 
alcoholic  solution  leaves,  on  evaporation,  a  wholly  amorphous  resin- 
like mass.  It  is  insoluble  in  water,  little  soluble  in  ether,  chloro- 
form and  benzin,  but  more  so  in  alcohol.  With  concentrated  sul- 
phuric acid  the  isolated  pigment,  as  well  as  the  chromoplasts,  takes 
first  a  greenish,  then  a  blue  color;  with  iodine  in  potassium  iodide  it 
gives  a  green. 
It  will  be  seen  from  this  that  while  the  red  pigment  of  Celastrus 
scandens  differs  from  xanthin  in  its  solubility,  it  agrees  with  it 
more  closely  in  regard  to  the  effect  of  sulphuric  acid  than  it  does 
with  carotin.  Another  striking  resemblance  with  xanthin  is  the 
resin-like  amorphous  residue  left  when  the  solvents  are  evaporated. 
The  coloring  matter  of  Celastrus  scandens  is  also  remarkable  for 
its  resistance  to  the  action  of  alkalies.  Boiling  with  potassium 
hydroxide  does  not  decompose  it. 
From  the  behavior  of  this  coloring  matter  with  solvents  and 
other  reagents,  we  must  conclude  that  in  it  we  find  a  connecting 
link  between  the  crystallizing  carotin  of  red  flowers  and  fruits  and 
the  amorphous  resin-like  xanthin  of  yellow  flowers,  and  these 
observations  tend  toward  the  confirmation  of  Courchet's  views,  that 
the  pigments  of  yellow  and  red  chromatophores,  having  the  prop- 
erty of  turning  blue  or  green  with  sulphuric  acid,  thus  distinguished 
from  all  other  pigments,  represent  a  group  of  closely  related  com- 
pounds, whose  composition  certainly  demands  further  investigation. 
6  Ibid. 
7  Ibid.,  p.  103. 
