﻿False 
  Atavism 
  207 
  

  

  no 
  changing 
  influence 
  of 
  the 
  climate 
  are 
  re- 
  

   quired 
  for 
  an 
  adequate 
  explanation 
  of 
  the 
  

   facts. 
  

  

  In 
  the 
  observation 
  quoted, 
  what 
  astonishes 
  us 
  

   most, 
  is 
  the 
  great 
  rapidity 
  of 
  the 
  change, 
  and 
  the 
  

   short 
  time 
  necessary 
  for 
  the 
  offspring 
  of 
  the 
  

   accidental 
  crosses 
  to 
  completely 
  supplant 
  the 
  in- 
  

   troduced 
  type. 
  In 
  the 
  lecture 
  on 
  the 
  selection 
  

   of 
  elementary 
  species, 
  closely 
  analogous 
  cases 
  

   were 
  described. 
  One 
  of 
  them 
  was 
  the 
  wild 
  oat 
  

   or 
  Avena 
  fatua 
  which 
  rapidly 
  supplants 
  the 
  

   cultivated 
  oats 
  in 
  bad 
  years 
  in 
  parts 
  of 
  the 
  

   fields. 
  Other 
  instances 
  were 
  the 
  experiments 
  of 
  

   Risler 
  with 
  the 
  " 
  Galland 
  wheat 
  and 
  the 
  ob- 
  

   servation 
  of 
  Bimpau 
  on 
  " 
  Rivett's 
  bearded 
  : 
  

   wheat. 
  

  

  Before 
  leaving 
  the 
  question 
  of 
  vicinism 
  and 
  

   its 
  bearing 
  on 
  the 
  general 
  belief 
  of 
  the 
  insta- 
  

   bility 
  of 
  varieties, 
  which 
  when 
  tested 
  with 
  due 
  

   care, 
  prove 
  to 
  be 
  quite 
  stable, 
  it 
  may 
  be 
  

   as 
  well 
  to 
  consider 
  the 
  phenomena 
  from 
  

   another 
  point 
  of 
  view. 
  Our 
  present 
  knowledge 
  

   of 
  the 
  effects 
  of 
  crosses 
  between 
  varieties 
  ena- 
  

   bles 
  us 
  to 
  formulate 
  some 
  general 
  rules, 
  which 
  

   may 
  be 
  used 
  to 
  calculate, 
  and 
  in 
  some 
  way 
  to 
  

   predict, 
  the 
  nature 
  of 
  the 
  impurities 
  which 
  nec- 
  

   essarily 
  attend 
  the 
  cultivation 
  of 
  allied 
  species 
  

   in 
  close 
  vicinity. 
  And 
  this 
  mode 
  of 
  cultivation 
  

  

  / 
  

  

  being 
  in 
  almost 
  universal 
  use 
  in 
  the 
  larger 
  nur- 
  

  

  