﻿THE 
  ISSUES 
  OF 
  LIFE 
  299 
  

  

  the 
  story 
  which 
  had 
  till 
  recently 
  all 
  the 
  expert 
  

   authority 
  behind 
  it, 
  is 
  that 
  the 
  larger, 
  stronger, 
  fiercer 
  Brown 
  

   Rat 
  killed 
  off 
  the 
  Black 
  Rat 
  everywhere, 
  and 
  by 
  competition 
  

   to 
  the 
  death 
  took 
  its 
  place. 
  But 
  the 
  account 
  of 
  the 
  matter 
  

   given 
  by 
  Dr. 
  Chalmers 
  Mitchell 
  is 
  very 
  different. 
  The 
  Black 
  

   Rat 
  is 
  far 
  from 
  being 
  extinct 
  in 
  Britain 
  ; 
  it 
  is 
  wild 
  and 
  shy, 
  

   much 
  more 
  active 
  than 
  the 
  Brown 
  Rat 
  ; 
  it 
  is 
  the 
  typical 
  

   barn 
  and 
  granary 
  rat. 
  The 
  Brown 
  Rat 
  is 
  more 
  of 
  an 
  out- 
  

   door 
  creature, 
  though 
  the 
  haunter 
  of 
  sewers 
  and 
  drains, 
  to 
  

   the 
  great 
  extension 
  of 
  which 
  it 
  probably 
  owes 
  a 
  considerable 
  

   part 
  of 
  its 
  success. 
  

  

  Let 
  us 
  allow 
  that 
  the 
  ranks 
  of 
  the 
  Black 
  Rat 
  have 
  been 
  

   increased 
  by 
  fresh 
  imports 
  ; 
  let 
  us 
  allow 
  that 
  it 
  once 
  was 
  

   the 
  ' 
  common 
  rat 
  ' 
  and 
  is 
  so 
  no 
  longer 
  ; 
  let 
  us 
  even 
  allow 
  

   that 
  if 
  representatives 
  of 
  the 
  two 
  species 
  are 
  shut 
  up 
  in 
  a 
  

   cage 
  together 
  (a 
  condition 
  of 
  which 
  there 
  are 
  few 
  counter- 
  

   parts 
  in 
  nature!) 
  the 
  brown 
  rats 
  will 
  kill 
  the 
  blacks; 
  yet 
  

   the 
  edge 
  has 
  been 
  taken 
  off 
  Darwin's 
  famous 
  illustration, 
  

   the 
  best 
  piece 
  of 
  evidence 
  he 
  adduced 
  in 
  support 
  of 
  his 
  thesis. 
  

   As 
  Dr. 
  Chalmers 
  Mitchell 
  says, 
  " 
  In 
  this 
  story 
  of 
  the 
  rats, 
  

   which 
  has 
  been 
  very 
  carefully 
  investigated, 
  there 
  is 
  no 
  trace 
  

   of 
  a 
  process 
  comparable 
  with 
  the 
  German 
  theory 
  of 
  war 
  

   as 
  an 
  instance 
  of 
  the 
  struggle 
  for 
  existence. 
  . 
  . 
  . 
  Each 
  

   species 
  has 
  its 
  different 
  aptitudes, 
  capacities, 
  and 
  prefer- 
  

   ences, 
  and 
  each 
  insinuates 
  itself 
  into 
  the 
  most 
  suitable 
  en- 
  

   vironment 
  ' 
  (1915, 
  p. 
  30). 
  The 
  internecine 
  competition 
  

   has 
  not 
  taken 
  place. 
  A 
  compromise 
  was 
  effected. 
  

  

  The 
  second 
  form 
  of 
  the 
  struggle 
  for 
  existence 
  is 
  between 
  

   animate 
  foes 
  of 
  entirely 
  different 
  kinds, 
  between 
  herbivore 
  

   and 
  carnivore, 
  between 
  birds 
  of 
  prey 
  and 
  small 
  mammals, 
  

   between 
  the 
  grass 
  and 
  the 
  other 
  plants 
  of 
  the 
  meadow, 
  be- 
  

   tween 
  the 
  thorns 
  and 
  the 
  seedlings 
  in 
  the 
  stony 
  ground. 
  

  

  