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Charles  Darwin. 
Am.  Jour.  Pharm- 
July,  1909. 
are  botanic  and  before  commenting  on  the  character  of  his  botanic 
studies  let  me  briefly  enumerate  his  most  important  botanic  writings. 
The  following  important  books  should  be  mentioned :  "  On  the 
Contrivances  by  which  Orchids  are  Fertilized  by  Insects,"  1862 ; 
"  The  Variation  of  Animals  and  Plants  Under  Domestication," 
1868  (two  volumes);  "  Insectivorous  Plants,"  1875;  "The  Move- 
ments and  Habits  of  Climbing  Plants,"  1875 ;  "  The  Effects  of 
Cross  and  Self-Fertilization  in  the  Vegetable  Kingdom,"  1876; 
"  The  Different  Forms  of  Flowers  on  Plants  of  the  Same  Species," 
1877;  "The  Power  of  Movement  in  Plants,"  assisted  by  Francis 
Darwin,  1880. 
Plis  minor  botanic  contributions  I  will  divide  for  sake  of  treat- 
ment into  the  following  categories :  ( 1 )  papers  dealing  with  the 
pollination  of  flowers;  (2)  papers  dealing  with  plant  distribution; 
(3)  papers  dealing  with  the  movements  of  plants;  (4)  papers  deal- 
ing with  questions  of  physiologic  botany.  Darwin  in  the  papers  of 
the  first  group  dealt  with  the  agency  of  bees  in  the  fertilization  of 
papilionaceous  flowers,  on  the  fertilization  of  winter  flowering  plants, 
on  the  fertilization  of  the  Fumariacese,  but  the  most  important  con- 
tributions included  in  this  group  were  those  on  the  two  forms  or 
dimorphic  condition  of  the  species  of  Primula  and  their  remarkable 
sexual  relations,  on  the  three  remarkable  sexual  forms  of  Catasetum 
tridentatum  and  on  the  sexual  relations  of  the  three  forms  of 
Lythrum  salicaria.  Darwin  retained  his  interest  in  questions  of 
geographic  distribution  even  after  he  had  settled  to  the  quiet  life  at 
Down.  Two  short  papers  are  of  interest  in  this  connection.  While 
on  the  Beagle,  he  had  studied  the  problems  connected  with  the 
origin  of  the  vegetation  of  oceanic  islands.  To  account  for  the 
distribution  of  many  plants  of  the  Pacific  Islands  the  botanist  must 
have  recourse  to  sea  currents  to  explain  the  phenomena.  Darwin's 
paper  on  this  subject  in  the  Gardener's  Chronicle  deals  with  the 
vitality  of  seeds,  his  second  paper  treats  of  the  action  of  sea-water 
on  the  germination  of  seeds  and  appeared  in  the  Journal  of  the 
Linnaean  Society. 
The  papers  dealing  with  the  movements  of  plants  may  be  dis- 
missed here  without  further  comment,  because  most  of  the  obser- 
vations recorded  in  them  were  published  in  his  more  pretentious 
works  on  the  same  subject.  I  can  find  only  two  papers  of  a  purely 
physiologic  character,  namely,  one  on  the  action  of  carbonate  of 
ammonia  on  the  roots  of  certain  plants,  and  another  on  the  action 
