﻿712 
  Mutations 
  

  

  dom 
  before 
  sinking 
  to 
  the 
  bottom 
  of 
  the 
  sea, 
  and 
  

   later 
  producing 
  the 
  vast 
  number 
  of 
  diverse 
  

   forms 
  which 
  now 
  adorn 
  the 
  sea 
  and 
  land. 
  

  

  All 
  these 
  evolutions, 
  however, 
  must 
  have 
  been 
  

   very 
  rapid, 
  especially 
  at 
  the 
  beginning, 
  and 
  to- 
  

   gether 
  cannot 
  have 
  taken 
  more 
  time 
  than 
  the 
  

   figures 
  given 
  above. 
  

  

  The 
  agency 
  of 
  the 
  larger 
  streams, 
  and 
  the 
  

   deposits 
  which 
  they 
  bring 
  into 
  the 
  seas, 
  afford 
  

   further 
  evidence. 
  The 
  amount 
  of 
  dissolved 
  

   salts, 
  especially 
  of 
  sodium 
  chloride, 
  has 
  been 
  

   made 
  the 
  subject 
  of 
  a 
  calculation 
  by 
  Joly, 
  and 
  

   the 
  amount 
  of 
  lime 
  has 
  been 
  estimated 
  by 
  

   Eugene 
  Dubois. 
  Joly 
  found 
  fifty-five 
  and 
  Du- 
  

   bois 
  thirty-six 
  millions 
  of 
  years 
  as 
  the 
  probable 
  

   duration 
  of 
  the 
  age 
  of 
  the 
  rivers, 
  and 
  both 
  fig- 
  

   ures 
  correspond 
  to 
  the 
  above 
  dates 
  as 
  closely 
  

   as 
  might 
  be 
  expected 
  from 
  the 
  discussion 
  of 
  evi- 
  

   dence 
  so 
  very 
  incomplete 
  and 
  limited. 
  

  

  All 
  in 
  all 
  it 
  seems 
  evident 
  that 
  the 
  duration 
  of 
  

   life 
  does 
  not 
  comply 
  with 
  the 
  demands 
  of 
  the 
  

   conception 
  of 
  very 
  slow 
  and 
  continuous 
  evolu- 
  

   tion. 
  Now 
  it 
  is 
  easily 
  seen, 
  that 
  the 
  idea 
  of 
  

   successive 
  mutations 
  is 
  quite 
  independent 
  of 
  

   this 
  difficulty. 
  Even 
  assuming 
  that 
  some 
  thou- 
  

   sands 
  of 
  characters 
  must 
  have 
  been 
  acquired 
  in 
  

   order 
  to 
  produce 
  the 
  higher 
  animals 
  and 
  plants 
  

   of 
  the 
  present 
  time, 
  no 
  valid 
  objection 
  is 
  raised. 
  

   The 
  demands 
  of 
  the 
  biologists 
  and 
  the 
  results 
  of 
  

  

  