[Python-mode] How to keeps emacs from launching a python shell

[olive]

I am using python-mode.el to edit python scripts (with FSF Gnu
emacs 23.3). Each time emacs enter python mode, it launches a python
interpreter (not visible by default but it is launched). Is it possible
to prevent that? I would like to be able to launch the interpreter when
I want it but not always by default.

Olive