156  True  and  False  Cactus  Gr  audi  floras. 
\m.  Jour.  Pharm. 
March,  1898. 
an  explanation  of  the  whole  difficulty.  The  generic  name  Cactus 
having  once  got  afloat,  merchants,  pharmacists  and  medical  men 
have  concluded  there  could  be  but  one  Cactus. 
CHEMISTRY  OF  CEREUS  AND  OPUNTIA. 
Cereus. — In  Mr.  Holmes'  article  in  the  Journal,  he  tells  us  that 
Bonnett  and  Bay-Tessier  discovered  an  alkaloid  which  they  named 
cactine.  Mr.  E.  H.  Farr  examined  the  drug  in  quantity,  and  found, 
among  other  substances,  "  glucosidal  resinous  bodies,"  and  "  also 
an  alkaloid  which  is  present  in  very  small  quantities  only."  The 
alkaloid  must  be  present  in  very  small  proportions,  for  I  failed  to 
get  any  reaction  with  Thresh's  reagent  with  three  fluid  drachms  of 
a  one  in  one  extract.  I  do  not  like  the  name  "  glucosidal  resinous 
bodies,"  which  Mr.  Farr  employs,  and  I  hardly  appreciate  the  mean- 
ing of  the  term,  but  I  am,  perhaps,  as  worthy  of  blame  myself,  for 
I  find  that  I  suggested  that  resins  might  play  the  part  of  glucosides. 
Of  one  thing  I  am  certain,  and  it  is  that  some  resins  do  reduce  weak 
Fehling's  solution  when  allowed  to  stand  for  an  hour  or  less  at  the 
temperature  of  a  .water-bath.  Cereus  stems  contain  a  large  propor- 
tion of  chlorophyll,  and  to  this  the  extracts  and  tinctures  of  the 
genuine  drug  owe  their  beautiful  green  color. 
Opuntia. — Still  referring  to  Mr.  Holmes'  essay,  Mr.  Farr  says: 
"  On  working  on  a  quantity  I  did  get  an  indistinct  reaction  for  alka- 
loids and  also  a  very  slight  reduction  with  Fehling's  solution." 
Further,  referring  to  the  resins,  Mr.  Farr  adds  :  "  The  most  charac- 
teristic one  is  but  very  slightly  soluble  in  aqueous  solutions,  and 
gives,  with  ammonia,  a  deep-yellow  color.  This  one,  with  at  least 
two  of  the  other  resins,  reduces  Fehling's  solution  on  boiling,  and  to 
a  fair  extent."  The  experience  of  Mr.  Farr  with  regard  to  the  resins 
of  Opuntia  agrees  in  many  points  with  that  of  Mr.  Hoseason  and 
myself,  but  we  found  no  alkaloid,  and  we  worked  on  large  quan- 
tities and  made  a  large  number  of  trials.  However,  a  significant 
point  is  that  Mr.  Farr  only  got  an  "  indistinct  reaction  for  alkaloids." 
The  flowering  tops  and  stems  of  Opuntia  contain  a  pigment  which 
I  imagine  is  xanthophyll,  and  hence  the  alcoholic  tinctures  and 
extracts  of  the  drug  have  always  a  yellowish  or  light- brownish 
color. 
How  came  Cereus  to  be  employed  as  a  heart  tonic  ?  In  view  of 
the  somewhat  dogmatic  opinion  I  have  expressed  of  the  worthless- 
