INFESTING  THE  MUSCLES  OF  THE  HUMAN  BODY. 
321 
immediately  engaged  in  physiological  investigations.  It  recently  happened  that  two 
medical  gentlemen  having  sat  down  to  partake  of  a  cod's  head  and  shoulders,  were  dis- 
agreeably interrupted  in  their  repast  by  the  appearance  of  a  large  lively  round  worm, 
which  on  the  first  cut  into  the  fish  escaped  therefrom,  and  began  to  coil  and  uncoil  itself 
on  the  edge  of  the  dish.  Now  this  worm  must  have  been  submitted  to  the  temperature 
of  boiling  water  for  at  least  half  an  hour,  and  the  Entozoa  would  thus  appear  to  en- 
dure with  impunity  extremes  alike  of  cold  and  heat. 
With  respect  to  the  cyst  of  Trichina  spiralis,  I  was  at  first  incUned,  from  the  prevaihng 
regularity  of  its  figure,  to  beUeve  it  to  be  the  Entozoon  itself,  or  a  part  of  the  Entozoon 
analogous  to  the  dilated  tail  of  the  Cysticerci.  Mr.  Hilton,  Demonstrator  of  Anatomy 
at  Guy's  Hospital,  who  appears  to  have  first  recorded  this  affection  of  the  human 
muscles  \  ascribed  it  to  the  presence  of  a  minute  species  of  Cysticercus,  not  being 
aware  of  the  existence  of  the  animal  to  which  the  presence  of  the  cysts  in  question  is 
owing.  The  difference,  however,  between  the  parasitic  animals  under  consideration  and 
the  Cysticerci,  is  at  once  obvious ;  the  true  Cysticerci  are  always  inclosed  within  an 
adventitious  cyst  of  cellular  membrane,  in  which  the  Hydatid  either  freely  floats,  or  at 
most  adheres  to  the  inner  surface  by  the  mouth  only  ;  whereas  the  present  cysts,  besides 
the  absence  of  the  peculiar  structure  and  pearly  sub  transparency  which  characterize 
the  true  Hydatid,  adhere  to  the  surrounding  parts  by  the  whole  of  their  exterior,  which 
is  covered  by  a  cellular  flocculency. 
But  admitting  the  similarity  of  the  outer  cyst  of  Trichina  to  the  outer  adventitious 
cyst  of  Cysticercus,  it  may  be  contended  that  the  inner  cyst  is  part  of  the  organization 
of  the  inclosed  worm.  Its  analogy  to  the  second  cyst  of  the  genus  Anthocephalus, 
within  which  the  elongated  body  of  that  worm  is  seen,  readily  occurs,  but  will  not  hold 
good  on  a  close  examination.  The  elongated  body  of  Anthocephalus  is  always  found  in 
organical  connexion  with  the  second  cyst ;  and  Rudolphi  observes,  that  the  point  of 
continuity  is  indicated  externally  by  a  depression  occasioned  by  the  inversion  of  the 
body  at  that  part.  In  the  Cysticerci  a  similar  appearance  is  frequently  observed,  from 
the  inversion  of  the  head  and  body  within  the  terminal  cyst ;  and  in  the  Coenuri,  where 
the  corresponding  bladder  is  common  to  many  armed  heads,  some  of  these  are 
generally  found  inverted,  while  others  are  projecting  externally.  In  all  these  cases, 
however,  besides  the  difference  of  structure  between  the  second  and  outer  cyst,  they 
are  always  perfectly  distinct  from  each  other,  and  readily  separable.  But  I  have  never 
been  able  to  effect  a  corresponding  separation  between  the  outer  and  supposed  inner 
cyst  of  Trichina,  or  to  demonstrate  satisfactorily  the  existence  of  the  latter  as  a  distinct 
'  See  '  Medical  Gazette'  for  February  2,  1833,  p.  605.  In  a  letter  from  Mr.  Hilton  to  Thomas  Bell,  Esq., 
■which  the  latter  distinguished  naturalist  has  kindly  communicated  to  me,  it  is  stated  that  three  subjects,  -with 
the  muscles  similarly  affected,  have  been  brought  to  the  dissecting-room  at  Guy's  Hospital  during  the  present 
season  (1834—5). 
