32 
Researches  on  the  Jalaps. 
/'Am.  Jour.  Pliarm. 
\      Jan.,  1888. 
the  stem  which  forms  the  upper  portion  of  the  typical  tiibercules  of 
jalap  is  a  principal  stera^  its  inferior  appendages  are  cotyledons,  and 
their  axillary  bud«  correspond  to  cree|)ing  branches. 
The  secondary  elements  of  the  stem  are  in  direct  continuation  with 
the  secondary  elements  of  the  root ;  from  this  it  follows  that  the  root 
which  forms  the  lower  end  of  the  tubercule  below  is  the  principal 
root.  The  part  comprised  between  the  points  where  the  cotyledons 
issue  and  the  point  of  insertion  of  the  principal  root  corresponds  there- 
fore to  the  hypocotyledonous  axis. 
This  investigation  alloAvs  of  the  conclusion  that  the  typical  tuber- 
cules  of  jalap  represent  the  stock  of  the  convolviilaceous  plants  which 
produce  them,  and  that  die  tuberized  portion  corresponds  to  hyper- 
trophy :  (a)  of  the  base  of  the  principal  stem ;  (6)  of  the  hypocotyle- 
donous base ;  (c)  of  the  region  of  insertion  of  the  principal  root  upon 
the  hypocotyledonous  axis ;  and  (d)  of  the  upper  part  of  the  principal 
root. 
I  have  studied  in  the  same  manner  the  various  tubercules  of  jalap 
that  never  present  the  remains  of  aerial  organs  at  one  of  their  extrem- 
ities, and  I  have  in  this  way  recognized  that 
(1)  Most  of  the  varieties  of  tubercules  represent  tuberized  roots  of 
different  orders ; 
(2)  Some  tubercules  represent  subterranean  stems,  which,  having  to 
play  the  same  physiological  role  as  the  radical  tubercules,  are  tuber- 
ized by  the  same  process  and  present  a  nearly  identical  structure. 
Finally,  comparison  of  the  three  commercial  kinds  has  shown  me, 
that  in  respect  of  structure  there  is  no  difference,  however  slight, 
between  the  different  kinds  of  true  jalap. 
From  the  materia  medica  point  of  view  the  jalaps  are  therefore 
princi])ally  formed  of  tubercules  which  correspond  to  the  stocks  of  the 
convolvulaceous  plants  that  produce  them ;  they  include,  besides,  a 
certain  number  of  tubercules  which  represent  tuberized  roots  of  differ- 
ent orders;  lastly,  tubercules  are  met  with  derived  from  tuberized 
subtenaneous  stems. 
I  will  now  add  some  pharmaceutical  observations  upon  jalap  and 
the  resin  extracted  from  it. 
In  none  of  the  published  analyses  of  jalap  is  mention  made  of 
oxalate  of  lime,  but  a  microscopic  examination  and  microchemic  tests 
detect  it  in  considerable  proportion  in  the  tubercules. 
I  am  unable  to  accept  the  opinion  of  M.  Andouard,  according  to 
