contributed package source codes

Is there a way for me to get the source code ( C/C++ or FORTRAN)  for a 
specific  R package ?

The source to contributed packages is in <CRAN 
mirror>/src/contrib/PACKAGES.html.  You can find your CRAN mirror by 
looking at the CRAN entry in options("repos").  (You may need to call 
chooseCRANmirror() first, if it hasn't already been called.)

The source to base packages is in the R source, also on CRAN.

Duncan Murdoch