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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  Yearly 
  identity 
  is 
  disturbed 
  by 
  the 
  presence 
  of 
  too 
  many 
  or 
  too 
  

   few 
  rings. 
  Surplus 
  rings 
  are 
  caused 
  by 
  too 
  great 
  contrast 
  in 
  the 
  

   seasons. 
  The 
  year 
  in 
  Arizona 
  is 
  divided 
  into 
  four 
  seasons, 
  two 
  rainy 
  

   and 
  two 
  dry. 
  The 
  cold 
  rainy 
  or 
  snowy 
  season 
  is 
  from 
  December 
  to 
  

   March, 
  and 
  the 
  warm 
  tropical 
  summer, 
  with 
  heavy 
  local 
  rainfall, 
  

   occurs 
  in 
  July 
  and 
  August. 
  Spring 
  and 
  autumn 
  are 
  dry, 
  the 
  spring 
  

   being 
  more 
  so 
  than 
  the 
  autumn. 
  If 
  the 
  snowfall 
  of 
  winter 
  has 
  not 
  

   been 
  enough 
  to 
  carry 
  the 
  trees 
  through 
  a 
  long 
  dry 
  spring, 
  the 
  cell 
  

   walls 
  in 
  June 
  become 
  harder 
  and 
  the 
  growing 
  ring 
  turns 
  dark 
  in 
  

   color 
  as 
  in 
  autumn. 
  Some 
  trees 
  are 
  so 
  strongly 
  affected 
  that 
  they 
  

   stop 
  growing 
  entirely 
  until 
  the 
  following 
  spring. 
  A 
  ring 
  so 
  pro- 
  

   duced 
  is 
  exceptionally 
  small. 
  But 
  others 
  near 
  by 
  may 
  react 
  to 
  the 
  

   summer 
  rains 
  and 
  again 
  produce 
  white 
  tissue 
  before 
  the 
  red 
  autumn 
  

   growth 
  comes 
  on. 
  This 
  second 
  white-cell 
  structure 
  is 
  very 
  rarely 
  

   as 
  white 
  as 
  the 
  first 
  spring 
  growth 
  and 
  is 
  only 
  mistaken 
  for 
  it 
  in 
  

   trees 
  growing 
  under 
  extreme 
  conditions, 
  such 
  as 
  at 
  the 
  lowest 
  and 
  

   driest 
  levels 
  which 
  the 
  yellow 
  pines 
  are 
  able 
  to 
  endure. 
  Such 
  is 
  the 
  

   condition 
  at 
  Prescott 
  or 
  at 
  the 
  6,000-7,000-foot 
  levels 
  on 
  the 
  moun- 
  

   tains 
  about 
  Tucson. 
  A 
  broken 
  and 
  scattered 
  rainy 
  season 
  may 
  give 
  

   as 
  many 
  as 
  three 
  preliminary 
  red 
  rings 
  before 
  the 
  final 
  one 
  of 
  au- 
  

   tumn. 
  In 
  a 
  few 
  rare 
  trees 
  growing 
  in 
  such 
  extreme 
  conditions, 
  it 
  

   becomes 
  very 
  difficult 
  to 
  tell 
  whether 
  a 
  ring 
  is 
  formed 
  in 
  summer 
  or 
  

   winter 
  (that 
  is, 
  in 
  late 
  spring 
  or 
  late 
  autumn). 
  Doubling 
  has 
  become 
  

   a 
  habit 
  with 
  that 
  particular 
  tree 
  — 
  a 
  bad 
  habit 
  — 
  and 
  the 
  tree 
  or 
  large 
  

   parts 
  of 
  it 
  can 
  not 
  be 
  used 
  for 
  the 
  study 
  of 
  climate. 
  

  

  But 
  let 
  us 
  keep 
  this 
  clearly 
  in 
  mind 
  : 
  This 
  superfluous 
  ring 
  forma- 
  

   tion 
  is 
  the 
  exception. 
  Out 
  of 
  67 
  trees 
  collected 
  near 
  Prescott, 
  only 
  

   4 
  or 
  5 
  were 
  discarded 
  for 
  this 
  reason. 
  Out 
  of 
  perhaps 
  200 
  near 
  

   Flagstaff, 
  none 
  has 
  been 
  discarded 
  for 
  this 
  reason. 
  Nearly 
  100 
  

   yellow 
  pines 
  and 
  spruces 
  from 
  northwestern 
  New 
  Mexico 
  have 
  pro- 
  

   duced 
  no 
  single 
  case 
  of 
  this 
  difficulty. 
  The 
  sequoias 
  from 
  California, 
  

   the 
  Douglas 
  firs 
  from 
  Oregon, 
  the 
  hemlocks 
  from 
  Vermont, 
  and 
  

   the 
  Scotch 
  pines 
  from 
  north 
  Europe 
  give 
  no 
  sign 
  of 
  it. 
  On 
  the 
  

   other 
  hand, 
  10 
  out 
  of 
  16 
  yellow 
  pines 
  from 
  the 
  Santa 
  Rita 
  Moun- 
  

   tains 
  south 
  of 
  Tucson 
  have 
  had 
  to 
  be 
  discarded 
  and 
  the 
  junipers 
  of 
  

   northern 
  Arizona 
  have 
  so 
  many 
  suspicious 
  rings 
  that 
  it 
  is 
  almost 
  

   impossible 
  to 
  work 
  with 
  them 
  at 
  all. 
  Fossil 
  cypresses 
  also 
  give 
  much 
  

   trouble. 
  

  

  The 
  other 
  difficulty 
  connected 
  with 
  yearly 
  identity 
  is 
  the 
  omis- 
  

   sion 
  of 
  rings. 
  Missing 
  rings 
  occur 
  in 
  many 
  trees 
  without 
  lessening 
  

   the 
  value 
  of 
  the 
  tree 
  unless 
  there 
  are 
  extensive 
  intervals 
  over 
  which 
  

   the 
  absence 
  produces 
  uncertainty. 
  A 
  missing 
  ring 
  here 
  and 
  there 
  

   can 
  be 
  located 
  with 
  perfect 
  exactness 
  and 
  causes 
  no 
  uncertainty 
  of 
  

   dating. 
  In 
  fact, 
  so 
  many 
  missing 
  rings 
  have 
  been 
  found 
  after 
  care- 
  

  

  