I have noticed that music and singing in common have a favourable influence on the production of the phenomena. This circumstance is, however, another cause for suspicion, because the noise of music and singing can drown that made by the medium in moving about. Although I cannot consider the reality of the luminous phenomena observed by me as being so well established as that of certain other phenomena, I will none the less give the result of the ascertainments I think I have made thereon. I indicate them with every reserve; but the analogy they present with the ascertainments I made relative to raps and movements without contact, appeared to me useful to point out. It is one of the reasons which made me believe in their probability first of all; it is also the indication of the presumable existence of some general law governing all these phenomena, however different in appearance they may be. The most important observations I have to make are, as before, the synchronism between the muscular action and the phenomenon; the tendency to personification; the physical fatigue experienced by all the experimenters after a successful seance. The reasons why I conclude in the existence of this synchronism, are based upon a great number of observations made with Eusapia and other mediums. It seemed to me, in my experiments with Eusapia Paladino, that this latter preferred the breath to any other movement for the production of lights. This conclusion is uncertain, because I have not had occasion to examine many luminous phenomena with the Neapolitan medium. My observations were more precise with the Bordeaux medium. Rubbing the hands together, rubbing the feet on the floor, breathing hard, squeezing hands tightly when the chain is formed; all this provoked the apparition of the curious luminosities I have spoken about. True, these were also produced spontaneously; but the movements executed appeared to me to have an action upon their manifestation. Here again, the relation with the muscular contraction rather than with the movement itself seemed to me to exist, but I could not verify this point with the same certitude as with raps and movements without contact.