II. Secondly, I have verified that the intensity of the raps is not in proportion with the synchronous movement. I am unable to affirm the accuracy of this statement with the same confidence as with the preceding one; but I have observed the fact in a great many circumstances. Thus, _e.g._ a very slight movement of the finger will sometimes determine a rap, quite as loud as the rap determined by the abrupt lowering of the whole arm. Again, a simple muscular contraction also will bring about the realisation of the phenomenon, without the execution of any apparent movement. This observation is of special interest, if I am not mistaken, for it tends to make one suppose that the energy which serves to produce the raps is independent of the movement executed in space, but is connected with the cause of that movement, _i.e._ with the nervous influx. It would be well if experimenters, more competent than I am in physiology, were to study these observations carefully; I sincerely hope this will be done some day. Richet might well undertake these researches, for no one is more competent than he is to analyse the facts I am pointing out. I think there is a close connection between psychical phenomena and the nervous system. What I have just said about the production of raps by the simple contraction of a muscle under a voluntary nervous influx is one of the reasons upon which I base my hypothesis. There are others. I have often questioned mediums about their sensations when the raps were being produced. They all acknowledged to a feeling of fatigue—of depletion—after a good seance. This feeling is perceptible even to observers themselves. I have tried to analyse my own sensations when the raps are heard; I have not arrived at any positive result. I cannot say I have any decided physical sensation; but my negative observation is only of interest, if compared with the different observations I made, in connection with the production of movements without contact. One of the mediums, with whom some of my best and clearest raps were obtained, tells me he experiences a feeling akin to cramp in the epigastric region when the raps are particularly loud. This medium is a clever and highly-educated man, one quite capable of analysing his own symptoms. It seems to him as though something emanated from his epigastrum.