Am.  Jour.  Pharm. ") 
April,  1896.  J 
Opuntia  Vulgaris,  Mill. 
171 
about  three-quarters  of  an  inch  through  its  greatest  diameter,  from 
which  it  tapers  unevenly  to  the  base,  as  shown  in  the  accompanying 
figure.  It  is  truncate  at  the  apex,  the  plane  of  which  is  the  base  of 
a  conical  cavity.  The  fruit  contains  about  thirty  seeds  and  a  pulp 
of  a  rich,  red  color,  and  an  acidulous,  sweet  taste.  The  average 
weight  of  the  pears  examined  was  about  20  grammes.  Of  this 
amount,  more  than  50  per  cent,  were  rind  ;  the  seed  constituted  from 
4  to  5  per  cent.,  leaving  less  than  half  to  be  made  up  by  the  pulp. 
The  early  formation  of  the  coloring  matter  is  of  special  interest ; 
for  almost  as  soon  as  the  pear  assumes  definite  shape  there  appears 
in  its  centre  a  speck  of  color,  which  increases  in  size  as  the  pear 
grows,  gradually  spreading  outward.  The  rind  being  the  last  por- 
tion to  change  color,  the  fruit  is  considered  to  be  ripe  when  the  out- 
side is  fully  reddened.  Along  the  west  coast  of  Florida  the  ripen- 
ing takes  place  about  the  first  of  December.  The  red  color  may  be 
obtained  as  a  juice  having  a  tinge  of  purple,  by  simple  expression. 
Prof.  Henry  A.  Smeltz,  of  Tarpon  Springs,  Florida,  to  whom  I 
am  indebted  for  valuable  information  concerning  the  development  of 
the  color,  informs  me  that  he  has  extracted  the  color  by  each  of  the 
following  means,  and  has  found  no  trouble  from  the  instability  of  it, 
even  when  obtained  from  half-grown  fruit : 
(1)  By  maceration  with  acetic  acid  (glacial  acetic  acid,  1  part;* 
water,  10  parts);  this  is  an  original  process  with  him. 
(2)  By  fermentation  ;  he  covers  the  fruit  with  water  and  sugar 
(water,  1  quart ;  sugar,  y2  pound).  Fermentation  will  proceed  far 
enough  in  about  a  week  at  the  temperature  of  21 0  F.  He  then 
filters  and  adds  sufficient  alcohol  to  arrest  further  fermentation. 
(3)  Maceration  with  alcohol. 
(4)  Boiling  with  as  little  water  as  practicable,  filtering  and  adding 
alcohol. 
In  all  these  processes  the  fruit  is  first  cut  into  small  pieces  in 
order  to  facilitate  the  extraction  of  the  color. 
The  author's  experience  with  the  third  method  was  not  one  of 
success.  One  hundred  and  fifty  grammes  of  the  undried,  ripened 
fruit  were  chopped  into  small  pieces  and  macerated  with  official 
alcohol  for  five  days.  The  fruit  imparted  to  this  solvent  a  deep 
wine-red  color.  The  solution  was  separated  from  the  undissolved 
material  and  allowed  to  stand.  After  a  period  of  two  weeks  the 
color  had  changed  to  a  light  brown,  and,  upon  further  standing, 
