^epfember.^o™'}    Recent  Literature  Relating  to  Pharmacy.  451 
of  the  existence  of  lecithin  or  of  any  other  phosphorus-containing 
substance.  It  was  discovered  that  the  mucus  with  which  prepara- 
tions of  gastric  juice  were  contaminated  contained  a  proteid  of  which 
phosphorus  is  one  of  the  constituents.  The  author  agrees  with 
Friedenthal  that  the  proteid  body  precipitated  from  solutions  of 
pepsin  by  heat  contains  a  carbohydrate  as  well  as  a  pentose  mole- 
cule. Pekelharing  was  able  to  study  to  better  advantage  a  substance 
obtained  from  the  mass  precipitated  by  heat,  which  substance  pos- 
sesses the  properties  of  an  acid,  soluble  in  water  on  the  careful  addi- 
tion of  an  alkali.  For  this  substance  the  author  proposes  the  name 
"  pepsin-acid,"  and  has  learned  to  recognize  it  as  one  of  the  splitting- 
products  of  pepsin.  This  body  belongs  to  the  class  of  proteids  cor- 
responding with  other  members  of  this  class,  both  in  the  nature  and 
the  respective  proportions  of  its  constituents,  and  differing  from  the 
entire  mass  precipitated  from  solutions  of  pepsin  by  heat  only  in 
respect  to  the  proportion  of  sulphur.  Pepsin  prepared  from  the 
gastric  mucous  membrane  of  the  pig  and  that  prepared  from  the 
gastric  juice  of  the  dog  may  be  placed  in  the  same  category.  The 
differences  between  them  may  be  ascribed  to  the  difficulty  with 
which  pepsin  is  extracted  from  the  mucous  membrane  in  its  pure 
form.  Both  varieties  are,  like  all  the  other  proteids,  levorotatory,  but 
there  is  no  relation  between  the  amount  of  rotation  of  the  plane  of 
light  and  the  reaction  of  the  solution.  According  to  the  author,  the 
fact  that  the  substance  obtained  from  the  mucous  membrane  pos- 
sesses sufficient  purity  for  a  proteid  body  indicates  that  this  excep- 
tionally active  pepsin  is  the  enzyme  per  se,  and  does  not  owe  its 
digestive  power  to  the  presence  of  associated  bodies.  In  the  first 
place,  the  activity  of  pepsin  is  destroyed  by  heat  and  at  the  same 
temperature  as  that  at  which  albumin  is  coagulated.  In  the  second 
place,  as  soon  as  gastric  juice  is  deprived  of  its  albuminous  con- 
stituent through  semi-saturation  with  ammonium  sulphate,  it  loses 
its  zymotic  power.  Moreover,  the  presence  of  ammonium  sulphate 
is  to  a  large  degree  inhibitory  to  the  activity  of  pepsin.  It  has  pre- 
viously been  shown  by  the  author,  and  later  by  Nencki  and  Sieber, 
that  it  is  possible  to  prepare  active  solutions  of  pepsin  that  do  not 
give  the  reactions  for  proteid  bodies  ;  this  fact,  according  to  the 
author,  does  not  negate  the  idea  that  pepsin  is  an  albuminous  body. 
The  observers  just  mentioned  have  advanced  certain  facts  in  favor 
of  the  proposition  that  it  is  possible  for  the  same  molecule  to  dis- 
