44         Recent  Literature  Relating  to  Pharmacy.    {A  January  Pi898.m' 
The  test  for  rennin  is  as  follows:  10  c.c.  of  the  filtrate  of  the 
gastric  contents  are  neutralized  with  decinormal  solution  of  NaOH. 
To  this  10  c.c.  of  neutral  milk  are  added,  and  the  mixture  tested  at 
380  C.  If  rennet  be  present,  casein  will  form  in  ten  to  fifteen 
minutes.58 
The  test  for  the  zymogen  is  as  follows,  in  the  absence  of  the  fer- 
ment :  To  10  c.c.  of  the  filtrate,  made  slightly  alkaline,  add  2  c.c. 
of  a  1  per  cent,  solution  of  calcium  chloride;  then  10  c.c.  of  milk, 
and  heat  at  380  C.  If  rennet  is  present  casein  will  form.  It  is  rare 
to  find  a  condition  in  which  rennet  or  the  rennet  zymogen  is  wholly 
absent,  but  a  marked  diminution  of  these  substances  is  characteris- 
tic of  certain  morbid  conditions. 
In  some  cases,  therefore,  aid  may  be  derived  from  a  quantitative 
estimation  of  these  substances. 
The  quantitative  estimations  for  rennet  and  the  zymogen  are  as 
follows :  Part  of  the  gastric  filtrate  is  exactly  neutralized,  and  por- 
tions of  this  diluted  to  different  dilutions,  as  one-tenth,  one-fifteenth, 
one-twentieth.  Five  ex.  of  each  dilution  are  placed  with  5  c.c.  of 
neutral  milk  at  380  C,  and  the  dilution  at  which  the  ferment  ceases 
to  be  active  ascertained.  By  comparing  the  result  with  normal 
results,  any  diminution  and  the  amount  of  it  can  be  observed.  For 
the  zymogen  a  portion  of  the  filtrate  is  made  alkaline ;  different 
dilutions  made,  one-tenth  to  ^  ;  5  c.c.  of  dilution  placed  with 
1  c.c.  CaCl2,  plus  5  c.c.  of  milk;  and  the  dilution  where  action  ceases 
recorded. 
Full  tables  of  the  normal  amounts  of  the  rennin  and  its  zymogen 
in  the  normal  conditions  can  be  found  in  Friedenwald's  article  on 
the  subject.59 
(To  be  continued.) 
RECENT  LITERATURE  RELATING  TO  PHARMACY. 
EFFECTS  OF  MINERAL  SALTS  ON  THE  DEVELOPMENT  OF  PLANTS. 
M.  C.  Dassonville  has  made  a  series  of  experiments  on  the  effect 
of  solutions  of  various  mineral  salts,  especially  of  Knopp's  solution, 
on  the  growth  of  cereal  crops — wheat,  rye,  oat  and  maize — as  com- 
pared with  that  of  pure  water.    The  general  result  arrived  at  is  that 
58  Boas  :  Magenkrankheiten.    Loc.  cit. 
59  Friedenwald  :  Medical  News,  June  22,  1895. 
