254 
Studies  on  Pepsin. 
f  Am.  Jour.  Pharm. 
(     April,  1921. 
copper  wire,  preferably,  to  the  flower-stalk,  until  the  fruit  is 
mature. 
When  the  seeds  of  this  fruit  are  planted  they  germinate  and 
grow  into  adult  plants  that  possess  characteristics  partly  resembling 
one  parent,  partly  the  other.  These  are  termed  first  generation 
hybrids.  Seeds  collected  from  these  hybrids  give  rise  to  second 
generation  hybrids,  and  those  from  the  latter  originate  hybrids  of 
the  third  generation. 
It  is  surprising  that  so  little  work  has  been  done  up  to  the 
present  on  the  hybridization  and  selection  of  varieties  of  medicinal 
plants  to  the  end  that  staple  hybrids  may  be  procured,  yielding  a 
higher  percentage  of  active  constituents  than  the  presently  known 
plants.  If  hybridization  as  applied  to  varieties  of  Cinchona  plants 
has  resulted  in  doubling  the  yield  of  alkaloidal  principles  over  the 
amount  found  in  mossed  barks,  it  is  not  logical  to  assume  that  its 
application  to  many  other  drug  plants  would  offer  wonderful  pos- 
sibilities in  improving  their  quality  and  therapeutic  efficiency.'' 
ABSTRACTED  AND  REPRINTED 
ARTICLES 
STUDIES  ON  PEPSIN* 
By  Lewis  Davis  and  Harvey  M.  Merker. 
Chemical  Changes  in  the  Purification  of  Pepsin. 
The  question  of  the  chemical  composition  of  pepsin  has  occu- 
pied the  attention  of  a  number  of  investigators.  Following  the 
classical  researches  of  Pawlow  and  his  pupils,  Pekelharing  appears 
to  have  been  the  first  to  undertake  purification  of  the  enzyme.  This 
investigator  prepared  a  light  yellow  powder  which,  while  readily 
soluble  in  dilute  acids  and  sodium  chloride  solution,  dissolved  with 
difficulty  in  water  but  showed  strong  peptic  activity.  It  gave  reac- 
tions for  albumin,  but  was  believed  to  contain  a  soluble  phosphorus 
compound  as  an  impurity.    On  boiling  pepsin  solutions,  Pekelharing 
•"Contributions  from  the  Research  Laboratory  and  the  Department  of 
Glandular  Extracts,  Parke,  Davis  &  Co.  Reprinted  from  Pure  Products, 
February,  1921. 
