﻿438 
  Branner 
  — 
  Bacteria 
  and 
  the 
  Decomposition 
  of 
  Rocks. 
  

  

  Art. 
  XLIV. 
  — 
  Bacteria 
  and 
  the 
  Decomposition 
  of 
  Bocks 
  / 
  by 
  

   John 
  C. 
  Brannek. 
  

  

  Having- 
  had 
  occasion 
  recently 
  to 
  study 
  certain 
  features 
  of 
  

   rock 
  decomposition, 
  I 
  was 
  frequently 
  told 
  that 
  bacteria 
  

   were 
  important 
  agents 
  of 
  rock 
  decay. 
  I 
  here 
  indicate 
  as 
  briefly 
  

   as 
  possible 
  the 
  evidences 
  considered 
  and 
  the 
  conclusions 
  reached 
  

   in 
  regard 
  to 
  this 
  subject. 
  

  

  The 
  bacteriaceaz 
  or 
  schizomycetes 
  of 
  the 
  botanists 
  are 
  a 
  group 
  

   of 
  the 
  simplest 
  microscopic 
  fungi. 
  Fermentation 
  and 
  putre- 
  

   factive 
  processes 
  are 
  the 
  results 
  of 
  the 
  growth 
  of 
  certain 
  of 
  

   these 
  bacteria.* 
  

  

  The 
  discovery 
  that 
  organic 
  decay 
  was 
  a 
  process 
  of 
  bacterial 
  

   growth 
  seems 
  to 
  have 
  given 
  rise 
  to 
  the 
  idea 
  that 
  this 
  decay 
  

   extended 
  to 
  minerals 
  and 
  rocks 
  as 
  well. 
  In 
  1890, 
  Muntz, 
  

   speaking 
  of 
  decomposed 
  or 
  disintegrated 
  rocks 
  said,f 
  "In 
  

   applying 
  to 
  rocks 
  in 
  this 
  condition 
  the 
  word 
  decayed, 
  which, 
  

   since 
  the 
  work 
  of 
  M. 
  Pasteur 
  is 
  so 
  clearly 
  explained 
  as 
  facts 
  

   connected 
  with 
  the 
  growth 
  of 
  microscopic 
  organisms, 
  we 
  uncon- 
  

   sciously 
  establish 
  between 
  these 
  two 
  orders 
  of 
  ideas 
  a 
  correla- 
  

   tion 
  confirmed 
  by 
  the 
  researches 
  mentioned 
  above." 
  The 
  

   italics 
  are 
  in 
  the 
  original. 
  In 
  this 
  article 
  Muntz 
  speaks 
  of 
  hav- 
  

   ing 
  found 
  bacteria 
  " 
  in 
  the 
  denuded 
  rocks 
  of 
  the 
  Alps, 
  the 
  

   Pyrenees, 
  the 
  Auvergue, 
  and 
  the 
  Vosges, 
  comprising 
  the 
  most 
  

   varied 
  mineralogical 
  types 
  : 
  granites, 
  porphyries, 
  gneiss, 
  mica 
  

   schist, 
  volcanic 
  rocks, 
  limestones, 
  sandstones. 
  f 
  .... 
  Often 
  

   the 
  action 
  of 
  the 
  micro-organisms 
  is 
  not 
  confined 
  to 
  the 
  sur- 
  

   face, 
  but 
  extends 
  into 
  the 
  depth 
  of 
  the 
  rock 
  mass. 
  This 
  is 
  the 
  

   case 
  with 
  the 
  so-called 
  rotten 
  rocks 
  of 
  which 
  the 
  particles 
  

   become 
  disengaged 
  and 
  separate 
  as 
  is 
  often 
  seen 
  in 
  limestones, 
  

   schists 
  and 
  granites. 
  In 
  decomposed 
  rocks 
  I 
  have 
  always 
  veri- 
  

   fied 
  the 
  presence 
  of 
  the 
  nitrifying 
  organism." 
  

  

  This 
  statement 
  of 
  Muntz 
  seems 
  to 
  have 
  given 
  rise 
  to 
  the 
  

   somewhat 
  prevalent 
  idea 
  that 
  rock 
  decay 
  is, 
  like 
  organic 
  decay, 
  

   a 
  process 
  of 
  bacterial 
  growth. 
  It 
  appears 
  to 
  have 
  been 
  accepted 
  

   without 
  question, 
  and 
  one 
  finds 
  occasional 
  references 
  to 
  the 
  

   work 
  of 
  bacteria 
  in 
  rock 
  decay 
  as 
  if 
  it 
  were 
  a 
  fact 
  as 
  well 
  estab- 
  

   lished 
  as 
  their 
  work 
  in 
  organic 
  decay 
  .J 
  

  

  Accepting 
  the 
  statement 
  of 
  Muntz 
  that 
  bacteria 
  are 
  found 
  

  

  * 
  A. 
  De 
  Bary. 
  Comparative 
  Morphology 
  and 
  Biology 
  of 
  the 
  Fungi, 
  etc. 
  ; 
  trans- 
  

   lated 
  from 
  the 
  German 
  by 
  Garnsey 
  and 
  Balfour, 
  Oxford, 
  J 
  887. 
  (Contains 
  bibli- 
  

   ography.) 
  Duclaux, 
  Chimie 
  biologique, 
  Paris, 
  1883. 
  Cornil 
  et 
  Babes, 
  Les 
  

   Bacteries, 
  2d 
  ed 
  , 
  Paris, 
  1886. 
  Hueppe, 
  Die 
  Methoden 
  der 
  Bacterienforschung, 
  

   Wiesbaden, 
  1885. 
  Writings 
  of 
  Pasteur, 
  Koch, 
  Lankester. 
  

  

  f 
  Comptes 
  Reodus, 
  ex, 
  1890, 
  1372. 
  

  

  % 
  Robert 
  Warington, 
  U. 
  S. 
  Dept. 
  of 
  Agriculture, 
  Exp. 
  Sta. 
  Bull., 
  No. 
  8, 
  p. 
  70 
  ; 
  

   H. 
  W. 
  Wiley, 
  Yearbook 
  of 
  the 
  U. 
  S. 
  Dept. 
  Agriculture, 
  1895, 
  p. 
  71. 
  

  

  