﻿Branner 
  — 
  Bacteria 
  and 
  the 
  Decomposition 
  of 
  Rocks. 
  441 
  

  

  Warington 
  also 
  shows* 
  that 
  subsoil 
  nitrification 
  is 
  more 
  

   active 
  during 
  dry 
  periods 
  because 
  the 
  opening 
  of 
  the 
  soil 
  by 
  

   cracks 
  admits 
  the 
  air, 
  without 
  which 
  it 
  cannot 
  take 
  place.f 
  

  

  In 
  other 
  words 
  nitrifying 
  bacteria 
  not 
  only 
  do 
  not 
  penetrate 
  

   the 
  rocks 
  themselves 
  to 
  considerable 
  depths, 
  but 
  they 
  do 
  not 
  

   even 
  penetrate 
  the 
  soil 
  to 
  a 
  depth 
  of 
  more 
  than 
  three 
  or 
  four 
  

   feet. 
  In 
  the 
  face 
  of 
  this 
  fact, 
  and 
  of 
  the 
  other 
  fact 
  that 
  our 
  

   granites 
  are 
  often 
  decomposed 
  to 
  depths 
  of 
  more 
  than 
  100 
  feet, 
  

   it 
  seems 
  quite 
  improbable 
  if 
  not 
  impossible 
  that 
  bacteria 
  are 
  

   responsible 
  for 
  this 
  deep 
  decav 
  or 
  for 
  any 
  considerable 
  part 
  

   of 
  it. 
  , 
  

  

  Prof. 
  G. 
  P. 
  Merrill 
  in 
  his 
  paper 
  on 
  the 
  principles 
  of 
  rock 
  

   weathering,^ 
  summarizes 
  the 
  subject 
  well 
  when 
  he 
  says 
  of 
  bac- 
  

   teria 
  that 
  "the 
  depth 
  below 
  the 
  surface 
  at 
  which 
  such 
  may 
  

   thrive 
  is 
  presumably 
  but 
  slight, 
  and 
  their 
  period 
  of 
  activity 
  

   limited 
  to 
  the 
  summer 
  months." 
  

  

  It 
  may 
  be 
  asked 
  whence 
  came 
  the 
  nitrates 
  now 
  in 
  the 
  soil, 
  if 
  

   not 
  from 
  the 
  rocks 
  of 
  the 
  earth. 
  I 
  do 
  not 
  undertake 
  to 
  

   answer 
  this 
  question, 
  and 
  only 
  suggest 
  that 
  the 
  nitrogen 
  is 
  con- 
  

   tributed 
  to 
  largely 
  by 
  the 
  nitric 
  acid 
  produced 
  by 
  electric 
  dis- 
  

   charges 
  in 
  the 
  atmosphere, 
  and 
  by 
  the 
  union 
  of 
  ozone 
  and 
  

   ammonium 
  in 
  the 
  air.§ 
  

  

  It 
  will 
  not 
  be 
  out 
  of 
  place 
  here 
  to 
  refer 
  to 
  other 
  statements 
  

   regarding 
  the 
  presence 
  of 
  bacteria 
  in 
  the 
  rocks. 
  

  

  Trouessant 
  speaks 
  of 
  Bechamp 
  as 
  holding 
  that 
  the 
  organic 
  

   substance 
  of 
  the 
  rhizopoda 
  of 
  the 
  chalk 
  has 
  retained 
  its 
  vital- 
  

   ity 
  in 
  the 
  rocks, 
  " 
  since 
  a 
  freshly 
  cut 
  piece, 
  taken 
  from 
  the 
  

   quarry 
  with 
  all 
  possible 
  precautions, 
  to 
  exclude 
  air-germs, 
  is 
  

   able 
  to 
  furnish 
  microbes 
  (bacterial 
  which 
  multiply 
  rapidly 
  in 
  a 
  

   favorable 
  medium."]! 
  This 
  he 
  is 
  said 
  to 
  have 
  demonstrated. 
  

   I 
  have 
  not 
  seen 
  this 
  statement, 
  which 
  is 
  probably 
  made 
  in 
  

   Bechamp's 
  large 
  work.^f 
  I 
  am 
  disposed, 
  however, 
  to 
  believe 
  

   that 
  there 
  is 
  some 
  mistake 
  about 
  this. 
  It 
  is 
  difficult 
  to 
  believe 
  

   that 
  plants 
  have 
  preserved 
  their 
  vitality 
  in 
  the 
  rocks 
  for 
  

   thousands 
  of 
  years. 
  It 
  is 
  not 
  difficult 
  to 
  believe 
  that 
  such 
  

   forms 
  may 
  have 
  been 
  washed 
  into 
  cracks 
  in 
  the 
  rocks, 
  or 
  that 
  

   they 
  may 
  have 
  been 
  introduced 
  in 
  some 
  of 
  the 
  many 
  ways 
  in 
  

   which 
  these 
  organisms 
  elude 
  our 
  watchfulness. 
  

  

  But 
  even 
  if 
  there 
  were 
  no 
  mistake 
  about 
  the 
  matter, 
  the 
  

   existence 
  of 
  the 
  original 
  bacteria 
  in 
  chalk 
  beds 
  and 
  the 
  decom- 
  

  

  * 
  Jour. 
  Chem. 
  Soc, 
  li, 
  118. 
  

  

  f 
  U. 
  S. 
  Dept. 
  of 
  Agriculture, 
  Exp. 
  Sta. 
  Bui., 
  No. 
  8, 
  p. 
  70. 
  

  

  \ 
  Jour. 
  Geol., 
  iv, 
  857. 
  

  

  § 
  Bericht. 
  deuts. 
  Chem. 
  Gesel., 
  viii, 
  1481. 
  

  

  || 
  Microbes, 
  ferments, 
  and 
  moulds, 
  by 
  E. 
  L. 
  Trouessant, 
  the 
  International 
  Sci. 
  

   Ser., 
  N. 
  T.. 
  1892, 
  p. 
  125, 
  292. 
  

  

  •[ 
  Les 
  Microzymes 
  dans 
  leurs 
  rapports 
  avec 
  1'heterogenie, 
  etc. 
  ; 
  par 
  A. 
  Bechamp, 
  

   Paris, 
  1883. 
  

  

  