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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  19 
  2 
  9 
  

  

  classified 
  by 
  characters 
  which 
  we 
  now 
  beheve 
  to 
  be 
  largely 
  immaterial- 
  

   size, 
  shape, 
  habitat, 
  and 
  any 
  other 
  obvious 
  features; 
  Mr. 
  Gladstone 
  

   thought 
  whales 
  were 
  fishes 
  and 
  bats 
  birds, 
  and 
  plenty 
  of 
  people 
  still 
  

   suspect 
  a 
  slowworm 
  of 
  being 
  a 
  snake. 
  About 
  150 
  years 
  ago 
  compara- 
  

   tive 
  anatomy 
  began 
  to 
  get 
  them 
  into 
  more 
  natural 
  groups, 
  and 
  evolu- 
  

   tion 
  added 
  the 
  criterion 
  of 
  descent 
  in 
  determining 
  the 
  system 
  which 
  

   prevails 
  at 
  present. 
  Much 
  the 
  same 
  has 
  happened 
  in 
  classifying 
  the 
  

   elements 
  into 
  something 
  better 
  than 
  a 
  series 
  of 
  arbitrary 
  pigeonholes. 
  

   Their 
  discovery 
  was 
  the 
  first 
  step, 
  much 
  more 
  difficult 
  than 
  the 
  

   apprehension 
  of 
  animal 
  species. 
  The 
  progress 
  of 
  chemistry 
  then 
  

   showed 
  that 
  they 
  fell 
  into 
  groups 
  akin 
  to 
  vital 
  genera 
  or 
  families 
  or 
  

   phyla 
  (we 
  can 
  not 
  guess 
  at 
  what 
  level 
  the 
  analogy 
  is 
  closest), 
  and 
  the 
  

   discovery 
  of 
  inorganic 
  evolution 
  and 
  isotopes 
  has 
  brought 
  their 
  

   relationships 
  to 
  a 
  suggestively 
  biological 
  position. 
  Atomic 
  weights 
  

   are 
  no 
  longer 
  of 
  any 
  great 
  importance; 
  what 
  matters 
  in 
  classifying 
  

   an 
  element 
  is 
  its 
  atomic 
  number 
  which 
  determines 
  its 
  position 
  in 
  the 
  

   periodic 
  table 
  and 
  is 
  a 
  summary 
  of 
  its 
  comparative 
  anatomy 
  and 
  a 
  

   clue 
  to 
  its 
  history. 
  An 
  element 
  (e. 
  g., 
  lead) 
  may 
  arise 
  by 
  more 
  than 
  

   one 
  line 
  of 
  descent, 
  which 
  is 
  what 
  a 
  biologist 
  would 
  call 
  "evolution 
  by 
  

   convergence." 
  The 
  isotopes 
  into 
  which 
  Aston 
  has 
  dissected 
  many 
  of 
  

   the 
  elements 
  correspond 
  to 
  the 
  groups 
  of 
  closely 
  allied 
  species 
  which 
  

   embarrass 
  the 
  systematist 
  and 
  with 
  which 
  bacteriologists 
  are 
  familiar 
  

   enough. 
  Perhaps 
  if 
  they 
  had 
  sugar 
  reactions 
  or 
  could 
  be 
  agglutinated, 
  

   or 
  indeed 
  had 
  a 
  few 
  more 
  perceptible 
  characters 
  of 
  any 
  sort 
  they 
  

   might 
  be 
  easier 
  to 
  distinguish. 
  

  

  (d) 
  If 
  a 
  man 
  and 
  a 
  bicycle 
  are 
  smashed 
  up 
  together 
  in 
  a 
  common 
  

   catastrophe, 
  the 
  man 
  mends 
  himself, 
  the 
  bicycle 
  does 
  not. 
  This 
  

   capacity 
  of 
  self-repair 
  is 
  one 
  of 
  the 
  greatest 
  characteristics 
  of 
  live 
  

   organisms; 
  indeed, 
  if 
  one 
  wishes 
  to 
  define 
  shortly 
  the 
  subject 
  matter 
  

   of 
  pathology 
  I 
  doubt 
  if 
  one 
  can 
  do 
  it 
  better 
  than 
  by 
  saying 
  that 
  it 
  

   is 
  the 
  study 
  of 
  how 
  organisms 
  resist 
  and 
  repair 
  injury. 
  They 
  repair 
  

   themselves 
  in 
  two 
  ways. 
  In 
  the 
  larger, 
  more 
  complicated 
  animals 
  

   we 
  find 
  very 
  highly 
  developed 
  a 
  capacity 
  for 
  individual 
  repair 
  which 
  

   we 
  see 
  daily 
  in 
  the 
  post-mortem 
  room 
  and 
  experience 
  continually 
  

   in 
  our 
  own 
  persons; 
  it 
  is 
  so 
  common 
  that 
  we 
  are 
  not 
  impressed 
  by 
  it 
  

   as 
  much 
  as 
  we 
  should 
  be. 
  Simpler 
  things, 
  such 
  as 
  bacteria, 
  have 
  

   little 
  of 
  this 
  power 
  of 
  personal 
  repair; 
  indeed, 
  I 
  doubt 
  whether 
  a 
  uni- 
  

   cellular 
  organism 
  under 
  natural 
  conditions 
  can 
  effectively 
  repair 
  and 
  

   recover 
  from 
  a 
  substantial 
  injury 
  any 
  more 
  than 
  can 
  the 
  individual 
  

   cells 
  of 
  higher 
  animals. 
  But 
  they 
  achieve 
  the 
  same 
  ends 
  by 
  other 
  

   means, 
  and 
  owing 
  to 
  their 
  numerical 
  abundance 
  and 
  their 
  high 
  capac- 
  

   ity 
  for 
  reproduction 
  they 
  can 
  allow 
  the 
  injured 
  individual 
  to 
  perish 
  

   and 
  readily 
  replace 
  him 
  with 
  a 
  new 
  one. 
  Individually 
  or 
  racially, 
  

   therefore, 
  organisms 
  repair 
  themselves. 
  Atoms 
  seem 
  to 
  be 
  able 
  to 
  

   do 
  the 
  same. 
  All 
  gross 
  matter 
  is 
  made 
  up 
  of 
  atoms, 
  each 
  of 
  which 
  

  

  