265 
Taken  in  conjunction  with  the  figures  given  above,  this  may 
indicate,  as  StuhlmannS  suggests,  that  the  intestinal  infection 
gradually  works  forward,  and  that  the  proboscis  is  infected  last.  If 
the  intestinal  forms  really  die  out  in  two  or  three  days,  the  reinfection 
might  be  explained  by  some  of  the  proboscis  forms,  which  are  almost 
always  present  in  the  hypopharynx,  being  ingested  with  a  succeeding 
feed. 
VI.  MORPHOLOGY  OF  FORMS  FOUND  IN  GL.  PALPALIS 
In  fresh  preparations,  as  in  stained  ones,  the  parasites  presented 
a  great  diversity  of  size  and  shape,  from  extremely  long  narrow  forms 
to  short  broad  ones.  One  variety  had  a  body  somewhat 
like  the  section  of  a  bi-convex  lens,  with  a  long,  lash-like  flagellum  ; 
a  second  variety  was  a  very  narrow,  rod-like  organism,  which  moved 
with  considerable  rapidity ;  a  third  variety  was  ‘  beaked,’  that  is,  the 
posterior  portion  was  narrow,  and  succeeded  by  a  more  or  less  central 
bulbous  portion  which  tailed  off  into  the  flagellum.  The  development 
of  the  undulating  membrane  varied  from  nothing,  to  one  which  was 
fairly-well  defined.  The  two  types,  long  thin  ones  and  short  clubbed 
ones,  could  almost  always  be  seen,  though,  of  course,  many  inter¬ 
mediate  forms  between  these  two  were  also  present.  In  those  flies  in 
which  the  parasites  were  few  in  number,  they  were  as  a  rule  of  the 
broad  short  type.  In  the  majority  of  cases  the  trypanosomes  were 
extremely  numerous,  and  in  a  few  instances  large  clumps  of  them  were 
seen  adhering  by  their  flagellate  extremities  to  the  gut  wall  towards  the 
distal  end  of  the  intestine,  similar  to  the  clumps  described  by  Novy, 
■  McNeal  and  Torreyi^  in  mosquitoes.  The  trypanosomes  composing 
these  clumps  moved  slowly  from  side  to  side.  In  addition  to  the  free 
forms  carrying  flagella,  rounded  motionless  parasites  devoid  of 
flagella  were  also  observed  in  fresh  preparations.  These  are 
apparently  derived  from  the  ‘  broad  ’  type  of  organisms. 
In  only  one  fly  were  the  parasites  observed  outside  the  true 
intestine.  In  the  one  referred  to,  a  few  were  seen  in  the  preparation 
from  the  proctodaeum.  This  fly  had  been  fed  on  a  dog  about  an  hour 
previously. 
Trypanosomes,  or  any  bodies  recognisable  as  derived  from  them, 
were  never  seen  in  the  salivary  glands,  malpighian  tubules,  testes,  fat 
bodies,  ovaries,  or  other  organs  of  the  flies. 
