330       SPECIES  OF  IPOM(EA  AFFORDING  TAMPICO  JALAP. 
4.  Its  color  varies  between  dark  grey  and  brown  ;  the  ex- 
tremes of  this  color  were  regarded  by  Cotton  as  black  and  brown 
varieties. 
5.  This  color  is  very  distinct  from  that  of  Payta  and  Savanilla 
rhatany. 
6.  The  origin  of  Para  rhatany  is  unknown. 
7.  The  substitution,  in  medicine,  of  Payta  rhatany  by  another 
is  inadmissible.  There  exist  in  regard  to  the  tannin,  chemical 
differences  which  deserve  to  be  investigated.  The  tannins  pre- 
dominating, or  exclusively  present  perhaps  in  Savanilla  and 
Para  rhatany,  produce  bluish  black  precipitates  w4th  iron  salts. 
—Schweiz.  WochenscJir.  f.  Fharm.,  1869,  227-231. 
J.  M.  M. 
OM    A    SPECIES    OF    IPOMGEA,    AFFORDING  TAMPICO 
JALAP  * 
By  Daniel  Hanbury,  Esq.,  F.R.S.,  F.L.S. 
Two  centuries  and  a  half  have  elapsed  since  Jalap,  the  tuber- 
cule  of  a  convolvulaceous  plant  of  Mexico,  was  introduced  into 
the  Materia  Medica  of  Europe.  The  botanical  origin  of  the 
drug  long  remained  unsettled,  evidence  of  which  exists  in  the 
fact  that  two  plants,  neither  of  which  yields  jalap,  have  in  suc- 
cession received,  and  still  retain,  the  specific  name  Jalaj^a.  The 
veritable  source  of  jalap,  however,  was  brought  to  light  between 
the  years  1827  and  1830, f  in  which  latter  the  plant  was  described 
by  Wenderoth  as  Convolvulus  Purga.  In  1833  it  was  figured 
by  Hayne  under  the  name  of  Ipomoea  Purga ;  but  in  1839  it 
was  transferred,  on  account  of  its  tubular  corolla  and  exsert 
stamens,  to  Choisy's  genus  Exogonium.  As  this  genus  has  been 
recently  united  to  Ipomoea  by  Dr.  Meisner,  it  appears  best  to 
return  to  the  name  proposed  by  Hayne,  and  to  call  the  true 
jalap-plant  Ipomoea  Purga. 
The  unsettled  condition  of  Mexico,  and  the  fluctuations  of  com- 
merce, have  alternately  depreciated  or  enhanced  the  value  of 
jalap,  and  have  led  to  the  occasional  importation  of  other  roots 
possessing  more  or  less  of  the  characters  of  the  true  drug.  Of 
*  From  the  author. 
fMr.  Hanbury,  as  a  just  historian,  might  well  have  noticed  the  labors 
of  Dr.  Coxe  and  Mr.  Nuttall  in  this  connection.  See  D.  B.  Smith's  paper 
Jour.  Philad.  Col.  Pharm.,  vol.  2,  April,  1830.— Ed.  Am.  Jour.  Pharm. 
