On  Entamoeba  serpentis 
by 
Dr.  ARISTIDES  MARQUES  DA  CUNHA  and  Dr.  O.  DA  FONSECA 
(With  plate  19). 
The  present  paper  is  a  supplement  to 
earlier  researches,  published  in  a  preliminary 
communication  (see  Brazil  — Medico,  Vol.  31, 
N°  34).  It  deals  w'th  an  Entamoeba,  descri¬ 
bed  by  us,  from  the  intestine  of  a  brazilian 
snake,  Drymobius  bifossatus,  which  was 
examined  for  parasitic  protozoa. 
We  have  little  to  add  to  the  general 
morphology,  and  only  wish  to  give  a  few 
more  particulars  about  the  changes  in  the 
appearance  of  the  nucleus.  They  are  like  those 
observed  by  HARTMANN  in  Entamoeba 
testudinis  HARTMANN,  and  may  be  consi¬ 
dered  in  both  cases  as  the  result  of  cyclic 
variations  of  the  caryosome. 
Though  we  did  not  give  much  time  to 
the  study  of  fresh  material,  we  noticed  some 
interesting  facts.  Live  entamoeba  of  this  spe¬ 
cies  are  generally  nearly  spheric,  except 
when  pseudopodia  are  formed.  They  move 
rather  quickly.  Their  protoplasm  is  neatly  di¬ 
vided  in  two  layers:  the  external  (ectoplasm) 
and  the  internal  (endoplasm)  containing  in¬ 
clusions,  mostly  of  bacteria.  No  inclusion  of 
red  bloodcells  was  observed. 
After  fixing  by  sublimate-alcool  (SCHAU- 
DINN)  and  staining  with  iron-hematoxylin 
fHEIDENHAIN),  the  entamoeba  shows 
a  well  marked  dimorphism  ;  the  two 
extremes  are  very  different,  but  all  interme¬ 
diary  stages  between  them  are  found. 
The  first  of  these  forms  (plate  19, 
figs.  1,  7  and  8),  is  larger  and  its 
outline  changeable  on  account  of  active 
movement.  The  difference  between  the 
broad  external  zone  of  hyaline  ectoplasm 
and  the  alveolated  layer  of  endoplasm  is 
well  marked.  The  nucleus,  surrounded  by 
the  endoplasm,  is  vesicular,  large  and  roun¬ 
ded,  the  central  caryosome  large  and,  as  a 
rule,  formed  of  several  granules  of  chromatin, 
suspended  in  a  less  chromophilous  stroma. 
The  caryosome  is  surrounded  by  a  large  li¬ 
quid  zone,  which,  though  generally  structure¬ 
less,  may  contain  a  few  small  chromatin  granu¬ 
les,  forming  a  continuous  layer  ;  this  layer  may 
be  more  developed  on  one  side  than  on  the 
other  (Plate  19  fig.  1). 
The  other  form  (PI.  19,  figs.  9,  11  and 
12)  of  the  entamoeba  is  generally  smaller, 
