230 
ON  THE  MATURATION  OF  FRUITS. 
The  lower  part  of  the  vessel  by  being  screwed  into  the  upper 
part,  as  showai  by  D,  fixes  the  solid  filtering  medium,  which 
arrangement  allows  us  to  change  the  latter  as  often  as  may  be 
required,  and,  thus,  special  filter  blocks  can  be  kept  for  certain 
valuable  liquids. 
The  apparatus  is  supplied  with  a  lid,  F,  to  prevent  evaporation. 
We  regard  this  as  one  of  the  most  ingenious  and  practical 
improvements  that  have  been  made  for  filters  for  some  time,  and 
doubt  not  that  it  will  come  into  very  general  use. —  Chemist  and 
Druggist^  Jan.  15,  1861. 
ON  THE  MATURATION  OF  FRUITS. 
By  mm.  Berthelot   and  Buignet. 
The  changes  which  fruits  undergo  during  ripening  constitute 
the  most  remarkable  phenomena  of  vegetable  physiology.  i!^oth- 
ing  is  more  interesting  than  to  see  fruit  lose,  little  by  little,  its 
astringent  and  acid  flavor,  and  acquire  the  sweet  and  agreeable  ' 
taste  which  renders  it  fit  for  food.  This  change  is  especially 
worthy  of  attention  in  the  case  of  a  fruit  detached  from  the 
plant  on  which  it  was  developed.  In  this  case,  in  fact,  the  fruit 
constitutes  a  complete  medium,  which  derives  nothing  more  from 
the  plant  which  formed  it,  all  the  ulterior  changes  it  undergoes 
resulting  from  the  reciprocal  metamorphoses  of  its  own  mate- 
rials. It  is  under  such  conditions  that  we  may  hope  to  study 
most  simply  the  play  of  these  metamorphoses  ;  to  comprehend, 
for  instance,  the  laws  presiding  over  the  formation  of  vegetable 
acids  and  over  the  saccharine  principles. 
AYe  have  undertaken  to  make  a  series  of  inquiries  on  this 
subject,  the  first  results  of  which  we  now  lay  before  the  Acade- 
my. The  results  were  obtained  two  years  since,  during  the  win- 
ters of  1858  and  1859.  Our  reason  for  mentioning  these  dates 
is  to  show  how  slow  and  laborious  such  researches  are ;  the  ex- 
act innumerable  analyses  and  experiments,  which  can  only  be 
carried  on  from  year  to  year,  because  certain  conditions  of  these 
experiments  are  supplied  by  Nature  and  cannot  be  produced  at 
will.  In  this  first  paper  we  propose  mainly  to  develope,  by  a 
special  example,  the  methods  we  employ  and  the  end  w^e  ^ave  in 
view,  not,  however,  pretending,  .as  yet,  to  give  definite  results. 
