598 
Observations  on  Cherry  Barks. 
/Am.  Jour.  Pharin. 
\  December,  1895. 
in  the  latter  respect  any  specimens  of  P.  Virginiana  that  the  writer 
has  before  tested.  This  difference  can  easily  be  accounted  for  by 
differences  in  climatic  conditions.  No  differences  were  observable 
between  the  bark  of  the  Eastern  and  Western  forms  in.  the  external 
markings,  excepting  the  purely  accidental  one  that  the  bark  of  older 
stems  in  the  Western  form  was  mostly  covered  with  growths  of 
crustaceous  lichens,  decking  the  surface  with  grayish  and  whitish 
patches  and  blackish  dots  and  lines.  The  fracture  and  the  color  of 
the  interior  surface  correspond  closely  with  those  of  our  Eastern 
form. 
Furthermore,  a  microscopic  study  does  not  reveal  any  considera- 
ble differences  between  the  Western  form  and  ours.  The  slight  differ- 
ences revealed  by  the  drawings  may  well  be  due  to  the  widely  dif- 
FiG.  3. — Starch  from  the  bark  of  Primus  demissa,  magnified  1,200 
diameters. 
ferent  conditions  of  growth.  There  are  the  wavy  and  oblique  med- 
ullary rays  that  characterize  all  the  species  of  the  group;  but,  as  in 
our  Choke  cherry,  the  rays  are  less  oblique  than  in  the  other  species 
thus  far  studied.  The  bast  areas  between  the  rays  show  wavy,  com- 
pressed sieve-tissues,  with  walls  in  the  older  portions,  irregularly 
thickened,  and  numerous  long,  slender,  lignified  bast  fibres  arranged 
irregularly,  singly  or  in  clusters.  These  fibres  are  frequently  not 
straight,  but  wavy,  particularly  in  the  neighborhood  of  the  medullary 
rays. 
Beyond  the  extremities  of  the  medullary  rays,  in  the  cortex  or 
middle  bark,  occur  also  numerous  sclerenchyma  fibres,  a  fact  which 
was  noted  in  my  previous  description  of  our  Eastern  form.  These 
