﻿382 
  Scientific 
  Intelligence. 
  

  

  II. 
  GEOLOGY 
  AND 
  NATURAL 
  HlSTORY. 
  

  

  1. 
  The 
  Tetracentron-Drimys 
  Question; 
  by 
  G. 
  R. 
  Wieland 
  

   (communicated). 
  — 
  Are 
  Tetracentron, 
  Trochodendron, 
  and 
  Dri- 
  

   mys 
  Specialized 
  or 
  Primitive 
  Types? 
  By 
  W. 
  P. 
  Thompson 
  

   and 
  I. 
  W. 
  Bailey, 
  Mem. 
  New 
  York 
  Bot. 
  Garden, 
  vol. 
  6, 
  August, 
  

   1916, 
  pp. 
  27-32, 
  pis. 
  2-4. 
  — 
  The 
  work 
  here 
  cited 
  has 
  been 
  con- 
  

   tinued, 
  but 
  is 
  recorded 
  in 
  its 
  simpler 
  phase 
  as 
  an 
  instance 
  where 
  

   botanists 
  disagree, 
  and 
  might 
  continue 
  to 
  do 
  so, 
  were 
  no 
  Paleo- 
  

   botanic 
  data 
  available. 
  As 
  in 
  so 
  many 
  instances, 
  the 
  evidence 
  

   involves 
  either 
  an 
  outright 
  contradiction, 
  or 
  appears 
  to 
  permit 
  

   both 
  positive 
  and 
  negative 
  inferences, 
  with 
  the 
  balance 
  in 
  favor 
  

   of 
  either 
  so 
  even 
  that 
  biased 
  opinion 
  is 
  difficult 
  to 
  avoid. 
  The 
  

   problem 
  in 
  itself 
  is 
  one 
  of 
  the 
  most 
  far 
  reaching 
  in 
  structural 
  

   botany, 
  aud 
  it 
  does 
  seem 
  that 
  the 
  larger 
  facts 
  of 
  the 
  fossil 
  record 
  

   may 
  be 
  conclusive. 
  

  

  The 
  genera 
  cited 
  are 
  of 
  primitive 
  wood 
  type 
  since 
  they 
  possess 
  

   diffuse 
  parenchyma, 
  and 
  show 
  no 
  vestiges 
  of 
  vessels 
  in 
  the 
  root, 
  

   the 
  seedling, 
  node, 
  leaf, 
  or 
  other 
  supposedly 
  conservative 
  regions. 
  

   The 
  fact 
  that 
  the 
  stem-wood 
  is 
  without 
  vessels 
  has 
  long 
  been 
  

   known, 
  as 
  also 
  in 
  Zygogynum. 
  But 
  it 
  had 
  been 
  contended 
  that 
  

   vessels 
  were 
  earlier 
  present, 
  aud 
  that 
  neither 
  the 
  Araucaroid 
  

   pitting 
  seen 
  in 
  Drimys, 
  nor 
  the 
  scalariform 
  wood 
  of 
  Trochoden- 
  

   dron, 
  could 
  then 
  be 
  analogous 
  to 
  such 
  features 
  in 
  coniferous 
  

   stems. 
  A 
  heavy 
  burden 
  of 
  proof 
  rests 
  on 
  these 
  views 
  ; 
  for 
  the 
  

   resemblance 
  to 
  the 
  tracheids 
  and 
  to 
  the 
  wood 
  of 
  pines 
  is 
  a 
  very 
  

   complete 
  one. 
  

  

  The 
  wood 
  structure 
  of 
  the 
  Magnoliaceae, 
  in 
  passing 
  from 
  

   Drimys 
  to 
  the 
  ' 
  ' 
  tulip 
  tree 
  ' 
  ' 
  is. 
  if 
  read 
  forward, 
  a 
  virtual 
  record 
  

   of 
  stem 
  evolution 
  from 
  cycadeoid 
  or 
  old 
  pine 
  -like 
  woods 
  to 
  dif- 
  

   ferentiated 
  angiospermous 
  woods 
  with 
  abundant 
  vessels. 
  But 
  

   if 
  read 
  backward, 
  that 
  is, 
  as 
  a 
  series 
  of 
  reductions, 
  post-Jurassic 
  

   evolution 
  within 
  the 
  Magnolia 
  group 
  and 
  its 
  allies 
  seems 
  to 
  lead 
  

   to 
  contradictory 
  end-results 
  ! 
  It 
  is 
  far 
  simpler 
  to 
  look 
  on 
  stem, 
  

   and 
  flower, 
  as 
  in 
  part 
  old. 
  still 
  generalized 
  and 
  even 
  plastic. 
  

   Furthermore, 
  in 
  Tetracentron 
  the 
  leaf 
  gap 
  with 
  its 
  subtending 
  

   tracheids 
  is 
  very 
  suggestive 
  of 
  that 
  of 
  the 
  cycadeoids, 
  — 
  a 
  com- 
  

   parison 
  which 
  does 
  not 
  lose 
  by 
  reason 
  of 
  abundant 
  scalariform 
  

   tracheids 
  in 
  both 
  cases 
  (Trochodendron). 
  It 
  is 
  only 
  the 
  stipular 
  

   feature 
  that 
  is 
  not 
  reconciled 
  (Cf. 
  pi. 
  4). 
  On 
  turning 
  to 
  the 
  

   main 
  problem 
  these 
  facts 
  appear 
  : 
  — 
  

  

  Firstly, 
  no 
  one 
  fails 
  to 
  see 
  that 
  there 
  has 
  been 
  much 
  paral- 
  

   lelism 
  in 
  wood 
  development 
  amongst 
  conifers, 
  and 
  also 
  amongst 
  

   angiosperms, 
  in 
  Cretaceous 
  time. 
  

  

  Secondly, 
  amongst 
  the 
  Cretaceous 
  conifers, 
  where 
  the 
  stem 
  

   record 
  permits 
  partial 
  interpretation, 
  disappearance 
  of 
  the 
  more 
  

   ancient 
  types, 
  and 
  modification 
  towards 
  the 
  recent 
  forms, 
  is 
  in 
  

   full 
  view. 
  Again 
  and 
  again 
  the 
  genera 
  are 
  most 
  difficult 
  to 
  

   place 
  because 
  simple 
  of 
  feature, 
  and 
  so 
  related 
  to 
  several 
  of 
  the 
  

  

  

  