The reason why some people see a ghost and some do not may be that some furnish sufficient ectoplasm for a manifestation, and some do not, while the cold chill, the trembling, the subsequent faint, may be due not merely to terror but partly to the sudden drain upon the psychic supplies.
Apart from such speculations, the solid knowledge of ectoplasm, which we have now acquired, gives us at last a firm material basis for psychic research. When spirit descends into matter it needs such a material basis, or it is unable to impress our material senses. As late as 1891 Stainton Moses, foremost psychic of his day, was forced to say, "I know no more about the method or methods by which materialized forms are produced than I did when I first saw them." Were he living now he could hardly say the same.
This new precise knowledge has been useful in giving us some rational explanation of those rapping sounds which were among the first phenomena to attract attention. It would be premature to say that they can only be produced in one way, but it may at least be stated that the usual method of their production is by the extension of a rod of ectoplasm, which may or may not be visible, and by its percussion on some solid object. It is probable that these rods may be the conveyers of strength rather than strong in themselves, as a small copper wire may carry the electric discharge which will disintegrate a battleship. In one of Crawford's admirable experiments, finding that the rods were coming from the chest of his medium, he soaked her blouse with liquid carmine, and then asked for raps upon the opposite wall. The wall was found to be studded with spots of red, the ectoplasmic protrusion having carried with it in each case some of the stain through which it passed. In the same way table-tilting, when genuine, would appear to be due to an accumulation of ectoplasm upon the surface, collected from the various sitters and afterwards used by the presiding intelligence. Crawford surmised that the extrusions must often possess suckers or claws at the end, so as to grip or to raise, and the author subsequently collected several photographs of these formations which show clearly a serrated edge at the end that would fulfil such a purpose.
Crawford paid great attention also to the correspondence between the weight of the ectoplasm emitted and the loss of weight in the medium. His experiments seemed to show that everyone is a medium, that everyone loses weight at a materializing seance, and that the chief medium only differs from the others in that she is so constituted that she can put out a larger ectoplasmic flow. If we ask why one human being should differ from another in this respect, we reach that barren controversy why one should have a fine ear for music and another be lost to all melody. We must take these personal attributes as we find them. In Crawford's experiments it was usual for the medium to lose as much as 10 or 15 lb. in a single sitting-the weight being restored to her immediately the ectoplasm was retracted. On one occasion the enormous loss of 52 lb. was recorded. One would have thought that the scales were false upon this occasion were it not that even greater losses have been registered in the case of other mediums, as has already been recorded in the account of the experiments of Olcott with the Eddys.
There are some other properties of ectoplasmic protrusions which should be noted. Not only is light destructive to them unless they are gradually acclimatized or specially prepared beforehand by the controls, but the effect of a sudden flash is to drive the structure back into the medium with the force of a snapped elastic band. This is by no means a false claim in order to protect the medium from surprise, but it is a very real fact which has been verified by many observers. Any tampering with ectoplasm, unless its fraudulent production is a certainty, is to be deprecated, and the forcible dragging at the trumpet, or at any other object which is supported by the ectoplasmic rod, is nearly as dangerous as the exhibition of a light.