502      OBSERVATIONS  ON  SOME  PRODUCTIONS  OF  MEXICO. 
choacan  root  of  commerce  was  not  that  of  a  Convolvulus,  and  I 
thought  then  that  it  belonged  to  a  Tamus  of  the  family  Diosco- 
rese.  I  am  sustained  in  this  idea  by  finding  subsequently  in  the 
Histoire  des  drogues  of  Colin,  printed  in  1619,  that  in  his  time 
they  sold  as  Mechoacan  the  root  of  the  Seal  of  our  Lady  (Tamus 
communis,  L.),  and  I  asked  myself  then  whether  the  root  of 
Mechoacan  of  commerce  was  the  result  of  a  fraudulent  substitu- 
tion executed  in  Europe,  or  if,  being  really  imported  from 
Mexico,  we  must  be  deceived  in  the  plant  producing  it. 
According  to  what  has  been  said  in  the  previous  article,  it 
becomes  almost  certain  that  the  root  sold  in  Europe  under  the 
name  of  Mechoacan  comes  from  Mexico,  and  that  it  is  due  to 
Asclepias  Contrayerva,  of  the  Mexican  flora. 
As  to  the  true  Mechoacan,  M.  Schaffher,  in  1854,  had  not 
yet  seen  the  plant  which  produces  it,  but  according  to  the  sam- 
ple which  he  had  sent  to  M.  Merck,  this  root  does  not  differ 
from  fusiform  or  Male  Jalap  of  Ledanois,  and  it  follows  that  we 
cannot  admit  that  M.  Ledanois  has  discovered  a  new  jalap ;  he 
has  only  found  a  root  which  preceded  jalap  in  its  application  to 
medicine. 
M.  Bourgeau  some  time  ago  sent  to  the  School  of  Pharmacy  a 
species  of  jalap  which  he  said  was  produced  by  a  species  of 
Ipomea  abundant  in  Pedregal,  in  the  valley  of  Mexico.  This 
root  has  close  relations  with  fusiform  jalap,  with  which  it  is  found 
mixed  in  commerce,  but  it  is  more  succulent,  and  more  amylace- 
ous ;  it  is  generally  of  a  pale  reddish-brown,  and  presents,  when 
cut  transversely,  a  compact  structure,  brown  marbled  with  black. 
These  differences  may  be  due  to  the  season  of  collection  or  the 
mode  of  drying.  Besides,  the  root  of  M.  Bourgeau  has  a  musty 
odor,  very  marked. 
Besides  the  foregoing,  M.  Guibourt  describes  the  following 
substances  : 
Chapuy  Yerba  de  las  animas  (Helenium  autumnale,  L.) — This 
plant  grows  abundantly  near  Puebla ;  all  parts  of  it  are  strongly 
sternutatory,  but  particularly  the  flowers  and  the  seed. 
Chia  (Salvia  hispanica),  the  seeds  of  which  possess  mucilagi- 
