7i8 
Urinary  Casts 
Am.  Jour.  Pharm. 
October,  1920. 
products  of  their  disintegration,  or  non-organized  constituents, 
as  urates.  Hyaline  casts  dijffer  from  cylindroids,  which  they  so 
closely  resemble: 
I  St.  Tube  casts  do  not  form  sharp  angular  bends,  as  found  in 
cylindroids. 
2nd.  Cylindroids  always  exhibit  a  longitudinal  striation,  and  are 
usually  considerably  longer. 
3rd.  Cylindroids  do  and  hyaline  casts  do  not  give  the  mucin 
reaction  (the  production  of  coarsely  granular  turbidity  (observed 
microscopically)  on  the  addition  of  acetic  acid). 
Waxy  {or  Colloid)  Casts. — ^The  term  waxy  has  been  one  of  con- 
siderable misunderstanding  and  confusion.  Colloid  is  a  better 
term  to  use.  The  term  waxy  should  only  be  used  for  those  casts 
that  possess  a  lardaceous  or  waxy  composition.  They  give  no 
precipitate  with  acetic  acid,  nor  do  they  swell  under  the  action  of  this 
acid.  Their  composition  possesses  all  the  characteristics  of  that 
widely  discussed,  ill-defined  and  yet  unknown  material,  called 
by  the  name  of  colloid  substance.  It  is  thought  that  these  casts 
are  formed  by  an  alteration  of  albuminoid  material,  produced  by 
degeneration  of  renal  epithelial  cells.  This  accumulating  in  the 
tubules,  probably  gets  mixed  with  other  exudations  from  the  blood 
vessels,  and  what  is  known  as  colloid  casts  result.  It  is  on  this  ac- 
count that  these  casts  are  found  most  frequently,  associated  with 
chronic  renal  diseases,  and  are  usually  indicative  of  serious  lesions. 
Colloid  casts  have  a  peculiar,  dull,  opaque  appearance  (being 
more  opaque  than  the  hyaline  casts),  always  broader  than  the  latter 
variety,  frequently  shorter,  but  may  vary  considerably  in  length, 
and  are  either  longitudinally  fissured  and  with  more  or  less  irregular 
broken  ends.  The  boarders  are  sharply  defined  and  show  indenta- 
tions. Colloid  casts  of  large  diameter  and  length  if  present,  can 
only  be  observed,  providing  great  care  is  used  in  the  treatment  of 
the  urinary  sediment.  At  times  they  may  possess  a  light  yellow 
color.  They  are  generally  straight,  rarely  convoluted,  and  granu- 
lar deposits  are  not  frequently  found  in  them. 
Granular  Casts. — Many  regard  these  casts  merely  as  hyaline 
material  in  which  are  embedded  numerous  granules.  From  the 
standpoint  of  accuracy,  this  is  a  mistake,  as  there  is  a  difference 
between  a  granulated  hyaline  cast  and  a  granular  cast.  The  latter 
are  short  thick  bodies,  possessing  a  somewhat  dark  appearance  and 
granules  throughout.    These  granules  consist  of  albumin  (in  rare 
