346     ON  THE  COMPOSITION  OF  THE  MUSCLES  OP  ANIMALS. 
ON  THE  COMPOSITION  OF  THE  MUSCLES  OF  ANIMALS. 
Br  MM.  Valenciennes  and  Fremy. 
As  in  their  investigation  of  the  eggs  of  animals,  the  authors 
have  examined  the  muscular  fibre  of  creatures  of  different  orders. 
The  fibres  were  freed  as  far  as  possible,  by  anatomical  means, 
from  aponeurotic  fibres,  nerves,  blood  vessels,  fat,  &c. 
In  the  analysis  of  the  muscles  of  the  vertebrate  animals,  they 
found  the  principal  constituent  to  be  creatine.  Besides  this  they 
contained  inosinic  acid  and  creatinine.  Here,  therefore,  they 
effected  nothing  more  than  a  confirmation  of  the  researches  of 
Chevreul  and  Liebig.  Creatinine,  however,  appears  to  be  more 
generally  diffused  in  the  animal  kingdom  than  was  supposed,  for 
it  occurred  in  the  muscles  of  all  the  Vertebrata ;  sometimes  it 
was  met  with  in  a  free  state,  when  it  was  recognizable  by  its 
alkaline  reaction,  and  sometimes  it  was  combined  with  phos- 
phoric acid. 
The  body  which  communicates  to  the  muscles  their  acid  re- 
action is,  in  some  cases  at  all  events,  lactic  acid ;  but  the  strong 
acid  reaction  of  the  muscles  is  usually  caused  by  the  presence  of 
acid  phosphate  of  potash,  KO,  2HO,  PO5.  This  salt  is  obtained 
by  extracting  the  muscles  with  weak  alcohol,  and  evaporating 
the  solution  to  the  consistence  of  a  syrup,  when  the  salt  crystal- 
lizes. 
The  quantity  of  this  salt  in  the  muscles  appears  to  stand  in 
connection  with  the  formation  of  bone.  It  was  always  found  in 
considerable  quantities  in  those  animals  which  possess  greatly 
developed  bones,  but  in  very  small  amount  in  the  Articulata  and 
Mollusca.  It  is  easy  to  see  that  this  salt  may  be  of  importance 
in  the  formation  of  bone,  as  direct  experiments  showed  that  this 
solution  converts  carbonate  of  lime  into  phosphate. 
This  phosphate  also  appears  to  be  not  without  influence  on 
the  production  of  a  phosphuretted  fat  which  is  contained  in  the 
muscles.  The  muscles  of  vertebrate  animals  contain  a  con- 
siderable amount  of  fat,  which  consists  of  variable  quantities  of 
oleine,  margarine  and  stearine.  Together  with  these  neutral 
fats  another  occurs,  which  in  its  general  properties  is  distinct 
from  the  neutral  fats.  It  is  obtained  by  extracting  the  muscles 
with  weak  alcohol,  which  does  not  dissolve  the  ordinary  fats.  If 
