37. The transfusion, which takes place between the incarnated and spiritual population of the same globe, operates in the same way between different worlds, either individually in normal conditions or by masses in special circumstances. There are then collective emigrations and immigrations from one world to another. From there it results in the introduction into the population of the globe of entirely new elements, new races of spirits coming to mingle with existing races, constituting new races of men. Now, as spirits never lose anything they have once acquired, they carry with them intelligence and intuition of the knowledge they possess. They impress, consequently, their character on the corporeal race they came to animate. There is no need of new bodies created for especial use. Since the corporeal species exist, they find them ready to receive them; they are simply new inhabitants. In arriving upon the Earth, they are at first a part of its spiritual population; then incarnate themselves like others.