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economic  reasons,  otherwise  the  races  of  plants  and  animals 
would  in  a very  short  time  far  exceed  the  food  supply. 
Darwin  recognized  this  principle  and  applied  it  as  a cause 
ior  the  survival  of  living  organisms  against  those  forces  that 
tended  to  deplete  the  population.  He  claimed  that  the  in- 
dividuals  that  survived  the  various  causes  for  depleting  the 
population  did  so  by  natural  fitness  through  the  use  of  intel- 
ligence, instinct  or  characters  that  enabled  the  individual  to 
escape  the  calamity.  Or  in  other  words,  the  individuals  that 
now  make  up  a population  of  plants  or  animals  are  the  result 
of  a natural  selection  based  upon  the  fitness  or  adaptation  to 
survive  the  exigencies  of  life.  Herbert  Spencer  afterwards 
applied  to  this  principle  the  term  “survival  of  the  fittest.” 
Darwin’s  principle,  thus  enunciated,  is  substantiated  by  a great 
number  of  instances  among  both  domesticated  and  wild  plants 
and  animals. 
From  the  time  of  Lamarck  and  Darwin,  numerous  investi- 
gators have  written  on  the  general  subject  of  variations  in 
plants  and  animals  and  their  significance.  The  plant  breeder, 
or  person  engaged  in  the  improvement  of  plants,  recognizes 
these  principles  and  makes  practical  application  of  them.  It 
should  be  said  here,  however,  that  the  principles  by  which 
plants  may  be  improved  under  the  hand  and  direction  of  man 
is  not  by  haphazard  methods.  The  sciences  underlying  these 
practices  are  just  as  definite  and  applicable  as  the  sciences  un- 
derlying medicine  or  other  professional  practices.  It  is  true 
that  much  progress  has  been  made  by  men  not  thoroughly 
trained  in  the  sciences  that  bear  on  this  subject,  but  it  is 
equally  true  that  permanent  progress  both  from  the  scientific 
as  well  as  from  the  practical  point  of  view  is  not  possible  by 
those  not  versed  in  the  sciences  relating  to  plant  improvement. 
For  the  purpose  of  indicating  the  scope  of  learning  that  is 
essential  to  the  proper  practices  of  this  activity,  the  follow- 
ing sciences  are  mentioned:  mathematics,  physics,  botany, 
geology,  physiology,  nutrition,  thremmatology,  cytology, 
agronomy;  and  the  languages,  French,  German,  Greek  and 
Latin  are  also  quite  essential ; and  best  of  all  is  the  exer- 
cise of  good  judgment,  for  in  no  other  line  of  scientific  en- 
deavor does  the  play  for  good  judgment  come  with  better  ad- 
vantage than  in  the  activities  of  plant  improvement.  It  is  to 
be  noted  that  the  languages  Latin  and  Greek  are  very  impor- 
tant in  this  connection,  for  so  many  of  the  terms  used  have 
originated  from  these  languages,  and  oftentimes  without  a 
knowledge  of  these  languages,  the  relations  and  significance 
of  terms  used  or  desired  to  be  used  may  not  be  brought  out., 
Likewise,  French  and  German  are  quite  essential  because 
much  of  the  progress  which  has  been  made  in  these  activities 
has  been  recorded  in  these  languages  and  one  may  not  hope 
to  keep  abreast  of  the  advance  of  these  sciences  without  being 
