434  Senega,  Euonymus  and  Quillaja.  {^vl^£^mn.' 
microscopical  test  can  be  established  for  distinguishing  either 
senega  from  the  other. 
In  detail  it  may  be  observed  that  the  No.  60  powder  of  senega 
Fig.  1.  Cross-section  Senega  (Northern  variety);  a,  cork  cells;  b,  paren- 
chyma ;  c,  woody  tissue  ;  d,  tracheae. 
shows  mainly  the  suber  and  the  parenchymatous  tissues  in  tolerably 
regular  masses,  while  the  woody  centre  is  but  rarely  observed.  The 
soft  parenchyma  is  sometimes  broken  longitudinally  and  sometimes 
e 
-  c 
Fig.  2.  longitudinal  section  Senega  (Northern  variety);  a,  cork  cells ;  6, 
parenchyma  ;  c,  parenchyma  ;  d,  woody  cells  ;  e,  tracheae. 
transversely,  so  that  we  get  appearances  characteristic  of  the  sec- 
tions made  in  these  two  directions. 
As  might  be  supposed  from  the  appearance  of  the  sections,  no 
difficulty  exists  in  distinguishing  apart  the  powders  of  senega  and 
