Board Thread:General Discussion/@comment-44061-20130307153642/@comment-11051098-20130919141810

Firemonkeyjoe wrote: No not their powers. But like when the the hollows go from being a Gillian to an Adjuchas and eventually to a Vasto Lorde. They eat other Hollows to increase their own Reiatsu, Reiryoku strength, speed, Endurance, and Durability. Until they can evolve. Like how Ichigo's Hollow form changed. Over time His inner Hollow/Zanpakutô spirit could have been "eating" the hollows he defeated. And because they are a part of each other they supplemented each others growth rate. Allowing his inner Hollow/Zanpakutô spirit evolve much faster than normal.

That's what I meant, that his inner hollow perhaps consumed a part of the reiatsu of every hollow Ichigo killed.