A_368 - Since, conceptually, we have chosen to use tree sap for our purposes (to make rubber, as food...) then, in the same way, we are still required to leave some of the our blood. Therefore the associations that collect blood to be used for transfusions should, at least in part, also have it used to fertilize trees. Alternatively, if you want, if you know an expert in the nursing profession you can also just ask to have a syringe of your blood taken which you can use to carry out fertilizations. It's a must.