8    .  Structure  of  Sangainaria  Canadensis.  {A™auua^yfSf5.m' 
showing  the  relationship  existing  between  secretion  cells  and  com- 
plex laticiferous  tissue. 
That  the  secretion  cells  contain  resins  beside  the  alkaloidal  prin- 
ciples present  in  the  drug,  is  clearly  evidenced  by  tests.  Moreover, 
it  seems  probable  that  the  salts  of  sanguinarine  are  more  abundant 
in  the  large  orange-red  secretion  cells  of  the  pith  and  outer  portion 
of  the  middle  bark,  while  those  of  the  closely  related  alkaloid,  chele- 
rythrine,  are  more  abundant  in  the  smaller  yellow  cells  and  laticifer- 
ous tubes  of  the  inner  bark  and  inner  part  of  the  middle  bark. 
Fig.  5- 
Sections  treated  for  twenty-four  hours  or  more  with  strong 
glycerin  showed  deposits  in  the  secretion  cells  of  stellate  masses  of 
yellowish- brown  crystals,  with  a  decided  diminution  of  the  inten- 
sity of  color  in  the  liquid  contents  of  the  cells.  The  crystals  polarize 
beautifully,  but  for  lack  of  time  their  chemical  nature  has  not 
been  investigated. 
A  number  of  drawings  were  made  in  the  course  of  the  study, 
illustrating  further  the  structure  of  the  rhizome  and  root.  These 
drawings,  together  with  one  from  the  author's  Laboratory  Exercises, 
