﻿470 
  MR. 
  J. 
  PARKINSON 
  ON 
  SOME 
  [Dec. 
  1 
  897, 
  

  

  incomplete 
  nature 
  of 
  the 
  fibrous 
  growths 
  which 
  form 
  the 
  band 
  

   itself 
  (PI. 
  XXXYI, 
  fig. 
  4). 
  

  

  These 
  spherulites 
  occur 
  frequently 
  in 
  fragments 
  and 
  segments, 
  

   which 
  are 
  often 
  placed 
  in 
  such 
  a 
  position 
  that 
  they 
  form 
  part 
  of 
  an 
  

   unit 
  whole, 
  the 
  missing 
  parts 
  being 
  represented 
  by 
  confusedly 
  

   crystalline 
  matter, 
  and 
  rendering 
  the 
  idea 
  of 
  an 
  originally 
  complete, 
  

   subsequently 
  dispersed 
  and 
  broken 
  spherulite, 
  improbable. 
  It 
  is 
  

   also 
  to 
  be 
  noted 
  that, 
  if 
  spherulitic 
  growth 
  had 
  been 
  set 
  up 
  after 
  the 
  

   final 
  cessation 
  of 
  fluxion 
  in 
  the 
  rock, 
  we 
  should 
  have 
  expected 
  that 
  

   a 
  complete, 
  and 
  not 
  a 
  partially 
  complete, 
  spherulite 
  would 
  have 
  

   formed. 
  Suppose, 
  for 
  instance, 
  that 
  some 
  part 
  of 
  a 
  magma 
  which 
  

   had 
  become 
  in 
  a 
  greater 
  or 
  lesser 
  degree 
  separated 
  from 
  its 
  sur- 
  

   roundings 
  be 
  placed 
  in 
  conditions 
  suitable 
  for 
  the 
  formation 
  of 
  a 
  

   spherulite; 
  then, 
  fluxion 
  being 
  inoperative, 
  the 
  resulting 
  form 
  

   would 
  be 
  a 
  sphere, 
  no 
  matter 
  what 
  the 
  shape 
  of 
  the 
  differentiated 
  

   area 
  might 
  be, 
  since 
  the 
  residual 
  peripheral 
  parts 
  would 
  not 
  

   participate 
  in 
  the 
  radial 
  growth. 
  

  

  This, 
  however, 
  as 
  already 
  stated, 
  is 
  not 
  the 
  case 
  here. 
  In 
  other 
  

   instances 
  the 
  spherulites 
  most 
  commonly 
  consist 
  of 
  fragments 
  of 
  

   ellipses, 
  and 
  the 
  banded 
  structure 
  characterizing 
  the 
  previous 
  

   rock 
  is 
  absent 
  (PI. 
  XXXVI, 
  fig. 
  5). 
  In 
  the 
  less 
  strikingly 
  spheru- 
  

   litic 
  parts 
  of 
  the 
  slide 
  there 
  is 
  decided 
  evidence 
  of 
  flow-movement, 
  

   into 
  which 
  the 
  radially-arranged 
  outer 
  zones 
  of 
  the 
  spherulites 
  pass 
  

   gradually, 
  so 
  that 
  they 
  have 
  no 
  definite 
  boundary 
  such 
  as 
  would 
  

   have 
  been 
  expected 
  if 
  their 
  growth 
  had 
  been 
  undisturbed. 
  

  

  When 
  closely 
  packed, 
  these 
  spherulites 
  have 
  a 
  tendency 
  to 
  

   mutually 
  interfere 
  so 
  as 
  to 
  produce 
  hexagonal 
  bounding 
  lines, 
  

   the 
  interior 
  well 
  defined 
  from 
  the 
  outer 
  parts 
  ; 
  in 
  others, 
  adjacent 
  

   members 
  may 
  have 
  a 
  common 
  and 
  incomplete 
  exterior, 
  and 
  

   there 
  are 
  occasional 
  cases 
  where 
  axiolitic 
  fragments 
  are 
  grouped 
  

   together 
  in 
  a 
  manner 
  which 
  suggests 
  that 
  a 
  curving 
  line 
  of 
  

   flow 
  has 
  been 
  a 
  factor 
  in 
  determining 
  their 
  present 
  position. 
  

   There 
  are 
  also 
  instances 
  of 
  adjacent 
  spherulites 
  the 
  outer 
  parts 
  of 
  

   which, 
  though 
  fairly 
  well 
  formed, 
  are 
  connected 
  by 
  lines 
  un- 
  

   doubtedly 
  due 
  to 
  flow, 
  while, 
  in 
  others, 
  part 
  of 
  a 
  spherulite 
  or 
  of 
  a 
  

   group 
  of 
  spherulites 
  may 
  be 
  formed 
  of 
  matter 
  which 
  has 
  an 
  appear- 
  

   ance 
  strongly 
  suggesting 
  movement. 
  If 
  this 
  had 
  preceded 
  

   spherulitic 
  growth 
  and 
  then 
  stopped, 
  there 
  would 
  seem 
  to 
  be 
  no 
  

   reason 
  why 
  these 
  malformations 
  should 
  exist 
  ; 
  and 
  it 
  seems, 
  more- 
  

   over, 
  that 
  any 
  late 
  renewal 
  of 
  movement 
  which 
  could 
  thus 
  modify 
  the 
  

   symmetry 
  would 
  have 
  distorted 
  the 
  remainder 
  to 
  a 
  greater 
  extent 
  

   than 
  the 
  slides 
  exhibit. 
  Spherulitic 
  tufts 
  may 
  be 
  seen 
  in 
  places 
  

   wedged 
  in 
  between 
  a 
  spherulite 
  with 
  which 
  they 
  are 
  more 
  or 
  less 
  in 
  

   continuity, 
  and 
  an 
  external 
  part 
  which 
  shows 
  flow-lines 
  and 
  into 
  

   which 
  they 
  grade. 
  Thus 
  they 
  appear 
  to 
  represent 
  material 
  which 
  

   was 
  displaced 
  outwards 
  by 
  fluxional 
  movement. 
  

  

  MM. 
  Pouque 
  & 
  Levy 
  l 
  have 
  figured 
  from 
  Gratadis 
  spherulites 
  

   disturbed 
  by 
  flow-movements 
  which 
  show 
  some 
  resemblance 
  to 
  

  

  1 
  Mem. 
  Carte 
  geol. 
  France, 
  ' 
  Mineral. 
  Microgr.' 
  1879, 
  pi. 
  xv. 
  fig. 
  1. 
  

  

  