Am.  Jour.  Pharru. 
July,  1909. 
Charles  Darwin. 
349 
Darwin  established  the  department  of  biology  known  to-day  as 
ecology.  With  Darwin  as  a  botanist  we  are  especially  concerned, 
so  that  we  may  refer  in  particular  to  work  which  he  did  in  plant 
ecology.  The  first  botanic  book  to  appear  was  a  little  treatise  on 
the  pollination  of  orchids  by  insects,  published  separately,  as  it 
was  too  large  to  be  incorporated  with  any  other  subject,  and  its 
object  was  to  show  that  the  contrivances  by  which  orchids  are  fer- 
tilized are  as  varied  and  almost  as  perfect  as  any  of  the  most  beau- 
tiful adaptations  in  the  animal  kingdom,  and  secondly  to  show  that 
these  contrivances  have  for  their  main  object  the  fertilization  of  the 
flowers  with  pollen  brought  by  insects  from  a  distant  plant.  One 
of  the  most  curious  of  the  orchids  studied  by  Darwin  was  Coryanthes 
speciosa,  the  flowers  of  which  are  very  large  and  hang  down.  The 
distal  part  of  the  lip  petal  forms  a  large  bucket  over  which  arise 
two  appendages  which  drop  fluid  into  it.  When  the  labellum  bucket 
is  full  the  fluid  overflows  by  a  spout,  which  is  over-arched  by  the 
column  which  bears  the  stigma  and  pollen-masses  in  such  a  position 
that  an  insect,  which  has  had  an  involuntary  bath  in  the  liquid  by 
falling  into  it,  is  compelled  to  force  its  way  out  through  a  narrow 
passage  so  placed  that  the  insect  first  brushes  its  back  against  the 
stigma  and  afterwards  against  the  viscid  disks  of  the  pollen-masses 
and  thus  removes  them,  to  be  carried  in  flight  to  another  flower. 
Darwin's  ecologic  observations  on  insectivorous  plants  beg'an 
after  his  curiosity  was  aroused  by  the  common  sundew.  He  writes  : 
"  During  the  summer  of  i860  I  was  surprised  by  finding  how  large 
a  number  of  insects  were  caught  by  the  leaves  of  the  common  sundew 
Drosera  rotundifolia  on  a  heath  in  Sussex.  I  had  heard  that  insects 
were  thus  caught,  but  knew  nothing  further  on  the  subject.  I 
gathered  by  chance  a  dozen  plants  bearing  fifty-six  fully  expanded 
leaves,  and  on  thirty-one  of  these  dead  insects  or  remnants  of  them 
adhered."  After  the  most  painstaking  experimental  study  of  the 
plant  Darwin  concludes,  "  The  results  have  proved  highly  remark- 
able, the  more  important  ones  being,  first,  the  extraordinary  sensi- 
tiveness of  the  glands  to  slight  pressure  and  to  minute  doses  of 
certain  nitrogenous  fluids  as  shown  by  the  movements  of  the 
so-called  hairs  or  tentacles ;  second,  the  power  possessed  by  the 
leaves  of  rendering  soluble  or  digesting  nitrogenous  substances,  and 
of  afterwards  absorbing  them ;  third,  the  changes  which  take  place 
within  the  cells  of  the  tentacles  when  the  glands  are  excited  in 
various  ways." 
