Am-ju^;i?ohiarm-}  Story  of  the  Papaw.  339 
supply  the  energy  needed  for  the  maintenance  of  vital  processes, 
In  other  words,  these  enzymes  digest  and  prepare  food  for  plant 
life  and  growth. 
J.  Reynolds  Green  has  shown  that  in  the  process  of  nutrition  in 
plants,  when  the  constructive  processes  are  active,  an  excess  of 
material  is  elaborated  and  deposited  in  temporary  reservoirs.  This 
material  is  utilized  by  a  process  of  digestion  brought  about  by  the 
agents  of  enzymes  or  ferments  which  are  formed  to  digest  these 
deposited  materials.  From  many  plants  we  have  been  able  to 
separate  diastasic,  proteolytic,  glucosidal,  emulsifying  and  other 
ferments. 
The  papaw  is  a  plant  of  quick  growth.  It  rapidly  appropriates 
and  converts  decaying  vegetation.  Its  best  fertilizers  have  been 
found  to  be  dead  vegetable  and  animal  matter,  house  waste,  etc* 
This  suggests  that  the  presence  of  this  abundance  of  enzymic  power 
is  necessary  for  the  digestion  and  conversion  of  plant-food  material, 
and  that  the  material  is  prepared  for  incorporation  in  the  living 
plant  by  the  enzymes  present  in  the  latex. 
The  milky  juice  of  the  papaw  can  therefore  be  imagined  as  quite 
akin  to  the  gastric  or  pancreatic  juice  of  the  animal  organism. 
The  ducts  through  which  this  latex  flows  are  possibly  digestive 
tracts;  their  contents,  an  emulsion  of  partially  digested  proteid  and 
other  material,  under  transformation  preparatory  to  ultimate 
assimilation. 
Corrosive  Properties  of  the  Latex. — The  corrosive  action  of  the  latex 
has  been  recorded  ;  all  species  have  this  property  in  some  degree. 
Persons  who  handle  the  green  fruit  in  the  preparation  of  pickles  are 
troubled  with  raw  and  bleeding  fingers  and  are  forced  to  abandon 
the  work.  The  fresh  latex  will  irritate  the  mucous  membrane  and 
its  continuous  use  is  in  some  instances  very  escharotic.  This  prop- 
erty seems  more  manifest  in  certain  isolated  plants  of  apparently 
the  same  species.  This  is  true  not  only  of  the  Carica  papaya,  in 
universal  cultivation  by  the  natives,  but  also  in  other  varieties  the 
fresh  juice  will  blister  and  cauterize  almost  instantly.  A  caustic 
property  is  not  unusual  in  many  tropical  plants.  In  the  milk  of  the 
papaw  it  is  not  due  to  acid  constituents,  as  it  is  still  present  if  the 
slight  acidity  is  neutralized.  It  can  be  removed  by  chloroform  and 
ether,  and  is  either  removed  or  destroyed  in  some  of  the  processes 
of  separating  the  ferments  (precipitation). 
