Well, after looking at the pic, the pink one is likely toast. You may have a chance at rooting the yellow/orange one by cutting it off half way between the rot and the yellow (cheating closer to the yellow) let it callous over and then try and root it. If you try this with the pink one, do it in a separate pot. The soil you have them in looks quite heavy, what is it? tj

Thanks suemc, I think you've got it immediately! Looking at Rebutia images has quickly brought me to the picture in the link, of Rebutia heliosa, which seems to be a perfect match :) Here is a link that might be useful: Rebutia heliosa

Hi hanzrobo :) hi cmc :) Thanks for the replies! I initially severed on the hylo side, but you could see a lot of hylo in the sperical top cacti. I had to slice into the 'rebutia' to remove the triangular hylo. Not too happy about that part, but as you say, the season is on my side. Seems like you can stick just about anything in a bit of soil at this time and voila! New plant. I should dip in rooting powder right away? I'm not too sure about the order of things. Previously I've dried out my piece/cutting and then dipped in the hormone, but perhaps I've been doing things wrong...mind you with the fungicide that makes sense... The top is the healthiest most solid little green being inside . I've not sliced a cacti open before and used a very sharp Henckels knife - it went like a hot knife through butter it was that easy. The inside was just so...clean, green, and solid. I'll try to get some pics up...hubbie's in the market for a camera.

The red and yellow and pink can't photosynthesize, so that's the reason they are grafted. They are mutations lacking chlorophyll. If there was at least some green, they would be able to produce 'food'. They may grow roots and grow for a little while on their own, but usually don't survive for long. When grafted, they are getting fed by the rootstock which is a very vigorous plant, and quite often overgrows the colored one.