Any tree that has a large pith will be hard to be graft from, because the cutting is difficult to remove. If the pith is damaged, the graft will take in an unstraight manner, like with vines of all peach and apricot trees. Apricot trees have a very thin bark, and so it is necessary to graft them onto young trees whose own bark is not thick yet, such as the young shoots of prune trees or apricot trees. The graft will not take if the cutting gets wet. It is necessary therefore to graft in serein and mild weather, not too cold and not too windy. One must use old wood to graft, if one wants to graft on a tree that is already mature and quite big; because if this is the case, it will compress the cutting, and if the cutting is of young wood, it will not grow properly. But old wood resists the compression of old wood better than the young, because it is harder than young wood. But if the graft is done with only old wood, it will never grow beautifully, but will be frail and short and will take a long time to grow.