Let us complete the comparison. When the forest tree has ripened its fruits, the fruits burst open, the seeds escape from it, and fall into the soil, or are dispersed by the caprice of the winds. If the seeds fall into damp earth, they germinate, and, according to the laws of nature, young vegetables are produced, as we have previously explained. Multitudes of similar vegetables are produced by a single oak, a single cedar, a single chestnut tree. Just as the majestic adult tree lets fall from its thousand branches upon the soil the countless seeds which are to germinate there, so the spiritualized beings who dwell in the sun shed their emanations, their _animated germs_, upon all the planets. These germs, carried to the earth by the sunbeams, and falling upon our globe, produce the vegetables which afterwards give birth to the various animals, by the effect of the successive transmigrations of the same soul into the bodies of these creatures. We can now reply to the objection which we have placed at the beginning of this chapter: "How can the solar rays, being material substances, convey animated germs, which are immaterial substances?" When the physicists professed Newton's theory of the nature of light, in the theory of _emission_, it was necessary to regard light, and, consequently the solar rays, which produce it, as material bodies. But science has now rejected this theory, and replaced it by the theory of _undulation_, founded by Malus, Fresnel, Ampère, and all the constellation of great physicists and mathematicians of the commencement of this century. Facts, collected on every side, prove that the solar rays are not matter which transports itself from the sun to the earth, but that light, like heat, results from a primitive disturbance produced by the sun upon the ether, which is spread over all space. This disturbance communicates itself from molecule to molecule, from the planetary ether down to us, and produces the phenomena of light and heat. We cannot here develop at greater length, or explain more scientifically, the theory of undulations, which will be found sufficiently demonstrated in works on physics. We merely desire to prove that, according to the principles of modern science, the solar rays are not material bodies, but that they result from a simple vibration of the planetary ether. If, then, the rays of the sun are not material substances, there can be no difficulty in admitting that these rays (immaterial substance) are the bearers of the animated germs, which are immaterial substance.