AmAJp°rnr;i89b6arm'}         -Aril  of  Celastrus  Scandens.  185 
in  phaenogams,  in  regard  to  which  we  have  little  definite  descrip- 
tion, are  as  follows:  (1)  chlorophyll  green;  (2)  carotin,  in- 
cluding chlorophyll  yellow;  (3)  xanthin;  (4)  coloring  matter  of  Aloe 
flowers.  Our  knowledge  of  these,  with  the  exception  of  chloro- 
phyll, is  uncertain.  A  formula  is  attempted  only  for  carotin,  which 
is  said  to  be  C26H38. 
The  great  difficulty  experienced  in  investigating  these  pigments 
is  their  unwillingness  to  crystallize.  Carotin  is  the  only  one  of  these 
four  which  occurs  within  the  cell  in  a  crystalline  shape,  and  which 
can  be  again  crystallized  when  extracted  from  the  plant. 
Carotin  is  found  as  a  crystalline  secretion  in  the  root  of  Daucus 
Carota,  also  in  red  flowers  and  fruits.  It  imparts  a  blood-red  color 
to  carbon  bisulphide,  in  which  it  is  readily  soluble,  and  from  which 
it  may  be  obtained  in  the  form  of  a  crystalline  precipitate  by  the 
addition  of  alcohol.  I  found  that  the  pigment  of  the  aril  of  Celas- 
trus scandens  was  soluble  in  carbon  bisulphide,  forming  a  deep  red 
solution,  but  no  precipitate  was  visible  on  the  addition  of  alcohol. 
After  evaporation,  an  amorphous,  sticky  mass  resulted,  and  it  will 
thus  be  seen  that  it  differs  from  carotin  in  this  respect.  The  well- 
known  solvents  behaved  as  follows:  water,  no  visible  effect;  alcohol, 
50  per  cent,  no  visible  effect  on  the  chromatophores,  but  the  solu- 
tion was  slightly  tinged  yellow;  alcohol,  absolute,  more  soluble  and 
the  solution  of  a  deeper  tinge ;  ether,  about  like  50  per  cent,  alco- 
hol, but  a  greater  amount  of  yellow  residue  left  on  evaporation  ;* 
acetone,  about  like  50  per  cent,  alcohol ;  chloroform,  much  more 
soluble,  solution  deep  red ;  carbon  bisulphide,  a  deep  red  solution, 
similar  to  chloroform. 
Carotin,  according  to  Arnaud,  is  insoluble  in  water,  almost  so  in 
alcohol,  very  slightly  soluble  in  ether  and  most  so  in  chloroform 
and  carbon  bisulphide.  These  solutions  are  colored  yellow  to 
orange-yellow,  according  to  their  degree  of  concentration,  while  the 
solution  of  carotin  in  carbon  bisulphide  is  always  blood  red.5 
Comparing  this  statement  with  what  I  have  observed  regarding 
the  pigment  under  consideration,  we  find  that  there  is  a  close  simi- 
larity in  reference  to  its  solubility  and  that  of  carotin. 
With  concentrated  sulphuric  acid  the  chromatophore  changed 
first  to  a  greenish  color  and  then  to  a  decidedly  purple-blue.  This 
4  It  is  possible  that  the  yellow  matter,  with  which  the  cuticle  is  impregnated, 
influences,  to  some  extent,  the  color  imparted  to  solvents. 
5  Zimmerman,  Microtechnique,  p.  102. 
