But when I cut the root zone off, I saw a very invaded-with-rot plant. You can see the relationship of the roots to the vascular bundle. That is, in a normally grown cactus, the roots are connected to the vascular bundle. The vascular bundle is where the life of the plant exists. The roots transmit water and dissolved nutrients to the vascular bundle. (I've believed forever that the soul of a plant is in the roots.) The roots rotted and sent the rot up into the vascular bundle. This is a very diseased plant. I wouldn't normally have much hope for its recovery. I decided to cut more of the plant off to lessen the amount of fungus that the plant's immune system and the super glue have to fight.