Lymphoc3rtc8. — These  are  in  size  equal  to,  larger,  or  smaller  than
a  red  blood-cell;  the  nucleus  is  relatively  large,  round  as  a  rule
although  sometimes  deeply  notched,  and  central  in  position ;  the  pro-
toplasm is  scanty,  sometimes  hardly  seen,  in  other  cases  presenting  a
ragged  edge  around  the  nucleus,  and  may  appear  somewhat  granular  ;
on  the  cold  glass  these  cells  of  normal  blood  are  not  seen  to  move.
Normally  they  make  up  from  22  to  25  per  cent,  of  the  leucocytes.
On  a  warm  stage  those  in  lymphatic  leukaemia  especially  are  said  to
be  amoeboid.
Large  Mononuclears. — These  when  typical  are  two  or  three
times  the  size  of  a  red  blood-cell.  The  nucleus  is  often  round,  but
more  often  oval  in  shape  and  eccentric  in  position.  The  protoplasm
is  very  abundant  and  is  clear.  Although  these  cells  appear  non-
amoeboid,  yet  it  is  interesting  that  in  malaria  they  are  the  dominant
phagocytes.     They  are  about  i  per  cent,  of  the  total  number.
The  "transitional  cells"  of  Ehrlich  seem  to  be  old  forms  of
the  large  mononuclears.  They  are  the  largest  of  all  cells.  The
nucleus  is  pale  and  often  deeply  notched,  giving  it  the  so-called
**  saddle-bag"  or  the  wallet-shape.  The  protoplasm  is  abundant.  In  some
cells  may  be  seen  a  few  granules  in  the  proximity  of  the  nucleus.  These
constitute  from  i  to  3  per  cent,  of  the  leucocytes.
