366 
Note  on  Calabar  Beans. 
<  Am.  Jour.  Pharm. 
\      July,  1879. 
with  oblique  cracks,  and  containing  two  or  three,  or,  more  rarely,  only 
one  seed.  The  pods,  which  ripen  in  September,  dehisce  only  some 
time  after  maturity.  When  it  contains  only  one  seed  the  pod  is  almost 
fusiform,  when  more  than  one  it  is  slightly  constricted  between  the 
seeds,  in  this  respect  resembling  an  ordinary  French  bean.  He  gives 
the  native  name  as  "maxima  ia  muxito,"  and  the  habitat  in  primeval 
forests  near  Sobado-Bango,  Aquitamba,  Mata  irrgeni  de  Quisuculu  and 
Golungo  alto. 
Indeed,  his  description  so  closely  tallies  with  that  of  the  true  Calabar 
bean,  that  were  it  not  for  the  difference  in  the  stipules — which  in  the 
Mucuna  cylindrosperma  are  said  to  be  reflexed  and  persistent,  while  in 
Physostigma  venenosum  they  are  stated  to  be  deciduous — it  would  be 
impossible  to  distinguish  between  them.  Until  flowers  and  further 
specimens  of  the  two  plants  are  procurable,  it  would  indeed  seem  some- 
what doubtful  whether  the  Mucuna  cylindrosperma,  Welw.,  is  more 
than  a  variety  of  Physostigma  venenosum,  Balf.  Until  then,  it  should 
evidently  be  placed  in  the  genus  Physostigma,  under  the  name  of  P.  cylin- 
drospermum.  The  question  of  identity  is  also  one  of  some  pharmaceu- 
tical interest,  for  the  inquiry  naturally  arises,  whether  the  beans  differ 
in  medicinal  power  ? 
It  has  been  mentioned  to  me  by  Mons.  A.  Petit,  of  Paris,  that  he 
has  found  considerable  variation  in  the  yield  of  eserine  from  different 
samples  of  Calabar  beans,  and  that  he  was  puzzled  to  account  for  the 
fact.  Knowing  that  eserine  is  easily  decomposed  by  alkalies,  with  a 
reddish  coloration,  it  occurred  to  me  that  a  rough  test  of  the  presence 
of  that  alkaloid  in  the  cylindrical  beans  might  be  obtained  by  the  appli- 
cation of  liquor  potassae.  On  touching  the  cotyledons  with  this  alkali, 
I  was  surprised  to  find  that  while  the  true  beans  gave  a  permanent  pale 
yellow  tint,  the  cylindrical  ones  gave  a  deep  almost  orange  color  ulti- 
mately turning  to  a  greenish  hue  with  the  same  reagent,  thus  apparently 
indicating  greater  activity  than  the  ordinary  kind.  Exactly  the  same 
reaction  takes  place  with  the  cylindrical  beans  collected  by  Welwitsch 
and  described  in  the  "  Flora  of  Tropical  Africa,"  under  the  name  of 
Mucuna  cylindrosperma.  The  actual  yield  of  eserine  in  the  two  sorts  of 
Calabar  bean  is  now  under  investigation,  and  will  form  the  subject  of  a 
future  communication. 
For  practical  purposes  the  seeds  of  P.  cylindrospermum  may  be  thus 
