212 THE N RAYS OF M. BLONDLOT. 



the studies which this observation led him to pursue, he found that 

 the increase of brightness was most considerable in the vicinit}^ of a 

 muscle, and was greatest when the muscle was strongly contracted. 

 Nerves and nervous centers were afterwards found to produce similar 

 effects, and he was even able to follow in this manner the course of 

 certain nerves beneath the skin. These experiments suggested to 

 him that the human body, at least some portions of it, might be emit- 

 ting N rays, and he found that the emissions observed passed readily 

 thi'ough aluminum, paper, and other substances classed as transparent 

 to the N rays, and that the}^ were arrested by lead and moistened 

 paper which had been used by M. Blondlot as screens. The ra3^s were 

 further found to be reflected and refracted, and could l)e brought 

 to a focus by the aid of convex lenses, and appeared to have about 

 the same indices of refraction as the N rays themselves. It seemed 

 possil)le, however, that the human body acted merely as a reservoir, 

 storing up the rays like some other substances in which such action 

 had been observed b}^ M. Blondlot, but M. Char^^entier states that 

 after continuing nine hours in complete darkness the rays were still 

 emitted by the body, though perhaps a greater sensitiveness of the 

 eye under these conditions may have made it more easy to recognize 

 them. However, M. Charpentier is of the opinion that the human 

 body certainly emits N rays, and especially in those parts of it which 

 are in active use. 



From later experiments it was concluded that the lower animals, such 

 as the monkey and others, are active sources of the N rays, and that 

 here, as in man, the principal seat of the emission is in the muscles and 

 nerves. It was not alone the warm-blooded animals which appeared 

 to give rise to emission, but also the cold-blooded — frogs and others. 

 As in the case of metals and other substances experimented upon by 

 M. Blondlot, mechanical constraint, such as the compression of nerves 

 and muscles, greatly augmented the luminous effects. In order to 

 localize the observations in a convenient manner, M. Charpentier uses 

 a narrow lead tube from 2 to -t inches in length, of which one end is 

 pliu-ed in contact with the body to be examined and the other contains 

 the phosphorescent substance used as the indicator. He states that 

 he can thus trace out the regions of the brain which are active in 

 special functions, such as the "center of Broca," reputed to be the seat 

 of articulate language. 



It appears from Charpentier's later experiments that the physiolog- 

 ical emissions are not exclusively composed of N rays, but include 

 other kinds of radiation differing in some degree in their properties 

 from those which have been found associated with the N rays. 



