rmass not changing due to radii grow

Hi everybody,

I'm wondering why rmass is not changing while I let my radii of the particles grow?
A logical reason might be, that rmass is calculated (by the formula 4/3*PI*radius^3) just once - at the beginning of the simulation.
Is that right?
Where can I find it in the code?

By the way:
What does the "r" mean in "rmass"? :)