150 
Ballota  Hirsuta. 
Am.  Jour.  Pharm. 
March,  19 19. 
palisade  cells,  several  layers  of  spongy  parenchyma  cells  traversed 
by  collateral  bundles,  and  a  lower  epidermis  similar  to  that  of  the 
upper,  but  possessing  stomata.  Non-glandular  and  glandular  tri- 
chomes are  present  as  outgrowths  on  both  upper  and  lower  epi- 
dermis. They  are,  however,  more  numerous  on  the  lower  epi- 
dermis.   The  non-glandular  trichomes  are  either  simple  or  branched, 
Fig.  4.  Cross  section  through  one  of  the  stronger  veins  and  portion  of 
the  lamina  of  Marrubium  vulgare.  up.  ep.,  upper  epidermis ;  I.  ep.,  lower 
epidermis;  pal,  palisade  parenchyma;  sp.  p.,  spongy  parenchyma;  x,  xylem; 
ph.,  phloem;  t,  long-pointed  non-glandular  trichome;  bt1,  bt2,  branched 
trichomes,  more  or  less  stalked;  bt3,  sessile  branched  trichome;  gt,  gt2,  gt3, 
gt*,  several  types  of  glandular  trichomes.    X  I20. 
the  latter  type  predominating.  The.  simple  trichomes  are,  for  the 
most  part,  unicellular  and  almost  invariably  slightly  curved.  There 
occur,  however,  a  scattering  of  much  elongated,  characteristically 
curved  and  twisted  (in  dried  material)  unicellular  hairs  which  type 
predominate  on  the  stem,  giving  this  part  its  white-woolly  aspect 
(Fig.  5,  /).  In  addition  to  these,  uniseriate  two-celled  hairs  with 
the  distal  cell  long-pointed  and  bent  have  been  met  with  occasionally. 
