368 
Digitalis  Hairs. 
(  Am.  Jour.  Pharm. 
I     August,  1911. 
of  many  plants  active  principles  are  contained.  For  instance  the 
volatile  oils  yielded  by  the  Labiatse  are  found  in  the  glandular  hairs 
of  the  plants  comprising  this  family.  The  stinging  hairs  of  the 
nettles  are  peculiar  in  structure  and  while  of  a  non-g-landular  char- 
FlG.  2. 
Transverse  section  of  digitalis  leaf,  through  one  of  the  veins:  UE,  ui^per  epidermis;  P, 
chlorenchyma  (mesophyll),  containing  chloroplastids;  LE,  lower  epidermis;  G,  glandular  hairs 
jV,  non-glandular  hairs;  C,  coUenchyma;       tracheae  or  vessels;  S,  leptome  or  sieve. 
acter  yet  they  contain  irritating  substances.  Nothing  appears  to 
be  known  with  regard  to  the  nature  of  the  secretory  substances  in 
the  hairs  in  digitalis  yet  the  fact  that  in  certain  specimens  we  find 
a  preponderance  of  glandular  hairs  is  suggestive  that  whether  these 
substances  are  toxic  or  not  or  have  any  influence  upon  the  action 
