Howling:Donna and the Chameleon arch

One thing I've wondered, the Doctor was able to change his DNA from Time-Lord to Human using the chameleon arch, storing his conciousness in a fob watch. Was there anything on screen to suggest that he could not do the same for Donna? If he could do that, wouldn't that solve the problem of her conciousness being Time-Lord.

I've been thinking about possible reasons that it may not have worked, such as Donna not being fully Time-Lord so it wouldn't work on her, or the chameleon arch being broken, but it really confuses my why the Doctor wouldn't attempt to fix it then use it on her, making her Human again. Does anyone have any sort of idea why he didn't, or possible reasons why he didn't? The Thirteenth Doctor 18:51, August 3, 2010 (UTC)