﻿United 
  Kingdom 
  during 
  the 
  War. 
  119 
  

  

  coveries, 
  nearer 
  than 
  ever 
  before 
  to 
  some 
  rational 
  view 
  of 
  

   the 
  origin 
  of 
  a 
  land-flora 
  on 
  a 
  basis 
  of 
  observation, 
  and 
  

   in 
  this 
  the 
  Bryophytes 
  will 
  assuredly 
  take 
  a 
  natural 
  place. 
  

  

  The 
  comparative 
  anatomy 
  of 
  the 
  vascular 
  system 
  has 
  

   been 
  enriched 
  by 
  the 
  last 
  papers 
  left 
  complete 
  on 
  the 
  

   death 
  of 
  Gwynne-Vaughan 
  in 
  1915, 
  from 
  natural 
  causes. 
  

   Careful 
  analysis 
  of 
  the 
  structure 
  of 
  these 
  rare 
  ferns, 
  

   Stromatopteris 
  and 
  Platyzoma, 
  have 
  been 
  published 
  by 
  

   J. 
  K. 
  Thompson. 
  The 
  morphology 
  of 
  the 
  leaf 
  has 
  been 
  

   illuminated 
  by 
  comparative 
  study 
  of 
  the 
  juvenile 
  leaves 
  

   of 
  rare 
  fern-types, 
  by 
  F. 
  0. 
  Bower: 
  and 
  he 
  has 
  added 
  

   three 
  more 
  memoirs 
  during 
  the 
  war 
  to 
  his 
  Comparative 
  

   Studies 
  in 
  the 
  Phylogeny 
  of 
  the 
  Filicales. 
  

  

  A 
  striking 
  discovery 
  has 
  been 
  made 
  of 
  obligate 
  sym- 
  

   boisis 
  in 
  the 
  common 
  heather, 
  by 
  Dr. 
  M. 
  C. 
  Rayner. 
  4 
  

   The 
  Heath 
  family 
  is 
  well 
  known 
  to 
  have 
  a 
  fungus 
  living 
  

   in 
  the 
  cortical 
  cells 
  of 
  the 
  root, 
  forming 
  the 
  association 
  

   known 
  as 
  mycorhiza. 
  Miss 
  Rayner 
  has 
  demonstrated 
  

   by 
  pure 
  cultures, 
  following 
  lines 
  already 
  pursued 
  by 
  Prof. 
  

   Bernard 
  of 
  Poitiers 
  for 
  the 
  orchids, 
  that 
  the 
  common 
  

   heather 
  cannot 
  form 
  roots 
  without 
  the 
  presence 
  of 
  the 
  

   appropriate 
  fungus. 
  Sterilized 
  seedlings 
  do 
  not 
  pro- 
  

   gress 
  beyond 
  the 
  first 
  stages. 
  The 
  infection 
  normally 
  

   takes 
  place 
  from 
  the 
  tissue 
  of 
  the 
  ovary 
  and 
  seed-coat. 
  

   The 
  fungus 
  lives 
  in 
  the 
  growing 
  tissues, 
  and 
  continues 
  

   to 
  grow 
  through 
  them 
  to 
  the 
  ovary 
  and 
  seed-coat, 
  from 
  

   which 
  it 
  passes 
  on 
  germination 
  to 
  the 
  new 
  germ. 
  The 
  

   condition 
  of 
  dependence 
  is 
  similar 
  to 
  that 
  in 
  a 
  lichen, 
  and 
  

   in 
  both 
  cases 
  the 
  proof 
  of 
  the 
  dependence 
  is 
  given 
  experi- 
  

   mentally 
  by 
  successful 
  synthesis. 
  It 
  is 
  a 
  beautiful 
  demon- 
  

   stration 
  of 
  a 
  state 
  intermediate 
  between 
  immunity 
  on 
  the 
  

   one 
  hand 
  and 
  mortal 
  parasitic 
  attack 
  on 
  the 
  other; 
  a 
  

   state 
  of 
  mutual 
  tolerance, 
  which 
  finds 
  its 
  parallel 
  in 
  some 
  

   infections 
  of 
  the 
  animal 
  body. 
  

  

  Plant-Physiology 
  has 
  been 
  very 
  active 
  during 
  the 
  war, 
  

   and 
  often 
  in 
  lines 
  that 
  will 
  have 
  practical 
  applications. 
  

   A 
  book 
  entitled 
  "Some 
  recent 
  researches 
  on 
  Plant- 
  

   Physiology 
  " 
  by 
  Dr. 
  W. 
  E. 
  F. 
  Atkins 
  of 
  Dublin, 
  contains 
  

   an 
  account 
  of 
  comprehensive 
  experiments 
  on 
  the 
  saps 
  of 
  

   plants, 
  by 
  delicate 
  measurements 
  of 
  their 
  freezing 
  point, 
  

   This 
  well-known 
  physical 
  method 
  was 
  used 
  to 
  obtain 
  

   knowledge 
  of 
  the 
  sugar 
  and 
  salt 
  content 
  of 
  very 
  small 
  

  

  4 
  Annals 
  of 
  Botany, 
  1915. 
  

  

  