WHAT  TO  OBSEEVE  IN  LICHENS. 
365 
lichens  which  grow  on  rocks  or  trees,  and  which  cannot  be 
properly  studied  without  the  aid  of  the  microscope ;  among 
species,  belonging,  for  instance,  to  such  genera  as  Lecidea,  Le- 
canora,  Grophis,  Opegropha,  Calicium.  It  is  not  to  be  expect- 
ed that  the  tyro  should  make  these  microscopical  examinations 
or  discoveries  for  himself :  he  will  probably  require  the  assistance 
of  some  experienced  microscopist  or  lichenologist.  The  appli- 
cations of  lichens  to  the  arts  are  daily  becoming  more  numerous 
and  important.  New  dye-lichens  are  being  discovered  in  India 
and  the  East.  Again  recently  the  probability  has  been  shown, 
on  good  ground,  that  a  lichen — the  Lecanora  esculenta  of  Pallas 
— was  the  Manna  of  the  Bible.  The  colorific  capability  of  a 
lichen,  so  far  as  regards  a  red  or  purple  dye  of  the  nature  of 
orchill  or  cudbear,  may  be  readily  discovered  by  simply  macera- 
ting the  lichen — chopped  into  small  fragments  or  pulverised 
according  to  the  nature  of  its  thallus — in  a  weakish  solution  of 
liquor  ammonia — allowing  the  mixture  to  stand  a  few  days  in  a 
warm  part  of  the  house,  and  shaking  it  frequently,  so  as  to  ex- 
pose the  mass  to  the  action  of  the  air.  The  colorific  capability 
of  a  lichen,  so  far  as  regards  other  colors — chiefly  brown  and 
yellow — may  be  easily  ascertained  by  simply  boiling  the  lichen, 
chopped  or  pulverized  as  before,  in  a  small  quantity  of  water. 
Whether  and  how  much  mucilage  or  starch  a  lichen  contains 
may  be  ascertained  by  the  same  means  as  last  mentioned,  and 
allowing  the  mixture  to  cool,  when  it  will  gelatinize  more  or  less, 
if  it  contain  much  mucilage.  Lichens  are  very  easily  collected 
and  transported  ;  they  require  no  sort  of  preparation ;  they 
may  be  simply  allowed  to  dry  in  the  open  air  and  packed  as 
convenient.  Those  growing  on  trees  generally  require  the  piece 
of  bark  on  which  they  grow  to  be  sliced  oiF  with  a  knife,  and 
those  on  stones  the  piece  of  rock  to  be  broken  with  a  hammer. 
Both  may  be  wrapped  in  paper  like  mineralogical  specimens. 
In  all  cases  the  localities  and  dates  of  collection  should  be  men- 
tioned, and  any  further  information  as  to  uses,  &c.,  which  may 
be  known  to  the  collector. — Dr.  W.  Lauder  Lindsay^  in  Chem, 
News,  London,  March  30,  1861. 
