The first is that although Dr. Crawford has not yet succeeded in photographing the structure _in situ_, he has obtained a photograph of what appears to be the same substance issuing out of the medium. Furthermore, the existence of the structure has been confirmed by clairvoyants, and this fact, taken in conjunction with the photographic results and with what I said about "etheric" or "ultra-violet" clairvoyance in Chapter III, forces us once more to the conclusion that this elusive substance possesses the property of emitting or reflecting ultra-violet light. The second point is that the extrusion of this substance from the medium results in superficial insensibility, although she is in full possession of all her normal faculties. Dr. Crawford discusses this point at some length in an article which appeared in the _Psychic Gazette_ for September 1916. Into the minutiæ of the discussion I need not enter here. It is sufficient to say that the medium is to some extent insensitive and that in Dr. Crawford's opinion "It seems likely that the want of sensibility to heavy and varied reactions which undoubtedly occur upon the medium is due to some peculiar condition of her organism during the period of phenomena." Now, these various experiments although they may be individually weak do seem rather to hang together. There is an appearance of possible connection between the experiments of Joire and recent views on the "aura"; and it is possible that what MacDougal weighed and Baraduc photographed are the same thing. It is obvious that all these experiments ought to be checked and re-checked by independent investigators and further experiments undertaken to discover whether there is any real connection between them. But for the present purpose I think it legitimate to extrapolate and to assume that they are reliable and connected in the way that I suspect. The experiments of de Rochas, of Joire and of Kilner suggest that a temporary loss of sensibility is accompanied by the extrusion from the body of a sensitive substance of peculiar properties. In the Baraduc and MacDougal experiments a total and permanent loss of sensibility seems to be accompanied by the extrusion of a substance of somewhat similar properties. Finally in the case of Dr. Crawford's researches we find that the extrusion of an apparently very similar substance is again accompanied by a certain insensitivity. Somewhat similar conditions are to be found in cases of "materialisation"--compare, for example, the work of Dr. Schrenk-Notzing and Mme. Bisson or Dr. Geley's paper in Part I. of the "Annales des Sciences Psychiques" for 1919.