Read domain's cookie from subdomain with Rails

Question

Hi,

In order to store some Google Analytics data, I would like to access to GA "__utmz" domain's cookie (domain=.example.com) from my www subdomain (domain=www.example.com). Is it possible to read this domain's cookie from a subdomain ? If yes, how can I do that with Rails ?

cookies[:__utmz] doesn't seem to work with all browsers.

I know I could configure my app setting the cookie domain to '.example.com' in my production.rb (config.action_controller.session = { :domain => ".example.com" }), but I'd rather not (because I don't want my www-subdomain's cookie to be shared among all subdomains).

I hope my question is clear enough...

Thanks by advance for your help (and sorry for the possible mistakes in my language...)