188  PROF.  J.  W.  JUDD  ON  INCLUSIONS  OF  TERTIARY  [May  1 893, 
of  iron,  which  is  so  uniformly  distributed,  has  been  produced  by  the 
oxidation  and  hydration  of  trichites  of  magnetite  which  have  clearly 
been  formed  at  "the  same  time  as  the  felspar-needles  between  which 
they  lie.  These  plumes,  which  are  now  of  a  creamy  white  colour, 
are  evidently  identical  with  the  ‘  trichitic  spherulites ’  described 
by  Mr.  Whitman  Cross.1 
"  The  foxtail-like  plumes  all  exhibit  the  beautiful  radial  structure 
combined  with  a  concentric  arrangement  so  well  described,  alike  b) 
Messrs.  Iddings,  Whitman  Cross,  and  ltutley  (PI.  III.  figs*  8  &  9). 
Between  the  portions  of  the  mass  formed  by  the  phenocrysts,  the 
ordinary  spherulites,  and  the  two  kinds  of  plumes,  we  sometimes 
find  other  growths  which  would  seem  to  be  analogous  to  the  ‘  supple¬ 
mental  spherulitic  growths  ’ 2  of  Whitman  Cross. 
The  centres  of  all  the  spherulites,  both  large  and  small,  appear 
to  be  very  generally  formed  by  original  crystals  of  quartz  or  felspar, 
or  sometimes  by  well-developed  micropegmatite  groups  which  have 
escaped  fusion.  In  some  very  interesting  cases,  however,  masses  of 
the  original  micropegmatitic  rock,  from  8  to  10  millimetres  in 
diameter,  seem  to  have  almost  entirely  escaped  obliteration,  and 
they  form  the  centres  of  great  compound  spherulites  (Pl.  III. 
figs".  10  &  12).  These  masses  of  micropegmatite  are  usually  sur¬ 
rounded  by  a  crust  of  glass  with  fluidal  structure,  which  is  stained 
by  iron  oxides,  while  outside  the  whole  we  find  the  great  mass  of 
the  complex  spherulitic  growth  (PI.  III.  figs.  11  &  13). 
If  any  doubt  existed  as  to  these  spherulitic  masses  haying  been 
formed  by  the  partial  fusion  of  the  micropegmatitic  granite  of  the 
Cuillin  Hills,  such  doubt  would  be  at  once  removed  by  the  exami¬ 
nation  of  those  fragments  of  granite  which  are  thus  curiously  pre¬ 
served  as  the  nuclei  of  spherulites.  In  the  drawing  on  the  opposite 
page,  Miss  M.  Ileeks  has  succeeded  in  giving  an  admirable  represen¬ 
tation  of  one  of  these  granite-fragments,  as  seen  with  a  low-powered 
objective. 
There  is  considerable  diversity  in  the  general  appearance  of  the 
sections  of  these  complex  spherulites.  This  is  caused  by  the  vary¬ 
ing  extent  to  which  the  several  kinds  of  spherulitic  growth  take 
part  in  the  formation  of  the  compound  masses.  In  some  cases 
rounded  and  irregular  masses  are  found  to  be  built  up  of  an  aggre¬ 
gation  of  ordinary  spherulites,  with  only  a  small  amount  of  inter¬ 
mediate  or  ‘supplementary’  spherulitic  growth  between  them. 
In  other  cases,  like  that  figured  in  PI.  III.  fig.  7,  a  few  scattered 
spherulites  of  the  ordinary  type  are  seen  to  be  enclosed  in  the 
plume-like  m.asses  building  up  the  ‘  porous  spherulite.’  Others,  and 
these  perhaps  constitute  the  most  abundant  type,  consist  wholly  of 
plume-like  or  arborescent  masses  radiating  from  one  or  several 
centres  and  enclosing  the  phenocrysts  of  the  original  rock. 
In  some  cases  the  oxidation  of  the  outer  zones  of  a  spherulite  has 
given  rise  to  a  very  marked  contrast  between  its  brown  outer 
1  ‘Constitution  apd  Origin  of  Spherulites,  etc.,’  Bull.  Pbil.  Soc.  Washington, 
vol.  xi.  (1891)  p.  423. 
2  Ibid .  p.  424. 
