1  Tf) 
The  individual  darkly  stained  granules  were  usually  of  large  size, 
measuring  3/z  to  5//  in  diameter.  They  were  of  the  same  size  m  the 
cortex  as  in  the  medulla,  not  presenting  any  increase  in  size  as  the 
renal  pelvis  was  approached.  A  few  tubules  were  met  with,  both 
in  the  cortex  and  in  the  medulla,  containing  much  smaller  granules, 
measuring  from  2/z  to  less  than  0'5/«  in  diameter  (cp.  Fig.  37).  Ihese 
were  sometimes  very  dark,  almost  black  in  colour,  sometimes  less 
*  _  .  I 
deeply  stained,  occasionally  merely  lightly  tinted. 
Epithelial  cells  were  a  common  feature  of  the  plugs  (Figs.  37  to 
40).  They  were  of  large  size,  with  abundant  cytoplasm.  The 
nucleus  was  sometimes  darkly,  sometimes  lightly  stained,  or  had 
contracted  to  form  a  small  darkly  stained  mass,  the  chromatin  net¬ 
work  of  which  was  not  well  defined.  The  cytoplasm  usually  stained 
more  deeply  with  acid  dyes  than  did  that  of  the  epithelial  cells  lining 
the  tubule,  but  was  less  granular  in  aspect  than  the  latter. 
The  lightly  stained  debris  sometimes  seen  in  the  tubules  in 
addition  to  the  above  elements  was  in  part  made  up  of  well-defined 
fine  granules,  24  to  S//  or  less  in  diameter,  and  m  part  of  amorphous 
flocculent  material.  Every  transition  could  be  observed  between 
the  former  and  the  darkly  stained  granules  of  smaller  size  described 
above. 
The  most  striking  feature  of  the  material  contained  in  the  lumen 
of  the  renal  tubules  was  its  multiformity  and  irregularity,  which  was 
much  greater  than  that  observed  in  the  renal  casts  seen  in  the 
urine  during  experimental  haemoglobinuria  or  during  blackwater 
(Figs.  21  to  32). 
The  uriniferous  tubules  were  considerably  distended,  the  lumen 
of  the  convoluted  tubules  commonly  having  a  diameter  of  404  to  50/1 
(Figs.  33  to  40),  and  the  epithelial  lining  affected  being  correspond-i 
ingly  flattened.  The  same  distension  affected  also  the  cavity  of  tlie| 
Malpighian  capsules  (Fig.  33),  which  occasionally  contained  lightly! 
stained  finely  granular  deposit.  Beyond  flattening,  however,  no  otheij 
abnormal  change  was  recognisable  m  the  epithelial  cells  of  tlit| 
kidney.  The  nuclear  staining  was  unaltered,  and  cloudy  swellingj 
was  not  observed.  No  brown  granules  were  met  with  in  thf| 
epithelial  cells  of  the  uriniferous  tubules. 
