Am.  Jour.  Pharm.  \ 
July,  1897.  J 
North  American  Conifer  ce. 
357 
isolated  or  clustered  in  groups  of  several  or  many,  throughout  all 
except  the  youngest  portions  of  the  inner  bark.  They  were  quite 
numerous,  but  distributed  without  apparent  order.  They  were 
marked  with  numerous  very  fine  pore-canals,  and  very  numerous 
and  fine  concentric  lines.  Although  abundance  of  starch  was  found 
in  the  bark  of  Tsuga  Canadensis,  none  was  observed  in  the  bark  of 
T.  Mertensiana.  It  is  possible,  indeed  probable,  that  a  sample  of 
the  latter  collected  at  some  other  season  of  the  year  would  show  the 
presence  of  starch.  The  medullary  rays  in  both  barks  were 
observed  to  be  composed  of  single  rows  of  cells,  and  these  were 
radially  elongated  and  of  large  size  as  compared  with  those  of 
adjacent  tissues ;  but  those  of  T.  Mertensiana  were,  on  the  average, 
larger,  and  the  rays  in  this  species,  as  seen  in  a  longitudinal-tangen- 
tial section  were  composed,  on  the  average,  of  a  larger  number  of 
cells. 
These  differences  in  the  medullary  rays  are,  perhaps,  the  most 
constant  ones  between  the  two  barks.  In  both  barks  an  abundance 
of  calcium  oxalate  crystals  was  observed.  (See  Fig.  55.)  They 
were  mostly  in  the  form  of  long  prisms,  and  were  contained  in  rows 
of  elongated  cells  of  narrow  diameter,  which  traversed  the  bark  in 
the  direction  of  its  length.  The  crystals  were  frequently  associated 
in  the  containing  cells  with  resinous  and  coloring  matters.  In  form 
and  arrangement  they  did  not  differ  in  the  two  barks,  but  appeared 
to  be  rather  more  abundant  in  the  Pacific  Coast  species. 
Oleoresin  cells  appeared  to  be  about  equally  abundant  in  the  two 
species.  Those  that  did  not  also  contain  crystals  were  isolated  or 
in  rows  of  two  or  three,  and  the  cells  were  shorter  and  broader 
than  the  crystal  cells,  though  they  were  not  usually  so  large  as  the 
parenchyma  cells,  with  which  they  were  associated.  They  were 
scattered  through  the  inner  bark  without  apparent  order.  Besides 
the  oleoresin  cells  proper,  just  described  oleoresin,  was  seen  to  occur 
in  many  cells  not  especially  devoted  to  secretions ;  this  was  particu- 
larly true  of  the  cells  in  the  older  portions  of  the  bark. 
CHEMICAL  COMPOSITION. 
The  constituents  of  Tsuga  Mertensiana  do  not  appear  to  have 
been  investigated.  The  work  for  this  paper  was  mostly  confined  to 
an  estimation  and  examination  of  the  tannin  in  the  stem  bark.  The 
sample  used  in  the  investigation  was  collected  by  Professor  F.  E. 
