The  term  neutrophilic  pseudolymphocyte  has  been  suggested  for  those
cells  which  have  a  round  nucleus,  rich  in  chromatin,  surrounded  by  a
narrow  rim  of  protoplasm,  filled  with  neutrophilic  granules.  These
leucocytes  may  represent  small  myelocytes,  as  their  color  character-
istics, excluding  the  strong  basic  nucleus,  suggest  neutrophile  myelo-
cytes. Tiirk  employs  the  name  "stimulation  form"  for  moderately
'arge  leucocytes  having  a  single  round  weakly  basophilic  nucleus,  and
a  non-granular  cytoplasm,  which  stains  a  brown  color  with  the  triple
niixture.
Ikvelopfnent  of  Leucocytes. — Most  authorities  regard  the  bone-mar-
row and  the  lymphatic  tissues  as  the  seats  of  leucocyte  formation,  the
former  being  concerned  in  the  development  of  polynuclear  neutrophiles,
cosinophiles,  basophilic  and  hyaline  cells,  while  the  latter  appear  respon-
sible for  the  production  of  lymphocytes.  In  the  bone-marrow  are  found
Poups  of  cells,  " leucoblastic  areas,"  consisting  of  myelocytes  surrounded
"}'  polynuclear  elements,  while  erythroblastic  zones  are  present  princi-
P^ly  along  the  margins  of  vascular  spaces.  It  is  conceded  by  most  author-
ities that  the  polynuclear  neutrophile  is  developed  from  the  neutrophile
'^y^locyte,  the  polynuclear  eosinophile  from  the  eosinophile  myelocyte,
^'id  a  basophilic  cell  from  its  parent  marrow  cell.  In  the  transformation
of  the  myelocyte  into  the  polynuclear  leucocyte,  the  nucleus  undergoes
condensation  and  lobulation,  the  size  of  the  cell  decreases,  and  the  stain-
^H  reaction  of  the  nucleus  and  of  the  granules  intensifies.  The  large
"Mononuclear  or  hyaline  and  transitional  leucocytes  are  probably  formed  in
^ne  marrow.  The  lymphocytes  arc  derived  from  lymphatic  tissue,  the
small  form  b^inc:  the  progeny  of  the  large  cell.
260  MEDICAL  DIAGNOSIS.
