| Popis: |
By a number of methods it has been shown that the action of the light is on the organism directly, and not indirectly through the formation of some toxic substance in the medium. It is a well-established fact that the Schumann region of the spectrum is a region in which nearly all substances have strong absorption bands. While no studies have been made upon the absorption of protoplasm in this region of the spectrum, undoubtedly strong absorption does occur. Gelatin, which is a much simpler substance than protoplasm, is so opaque to the rays that the ordinary photographic plate cannot be used in photographing the Schumann spectrum. Special plates, in which the silver salts are for the most part deposited on the surface of the gelatin, must be used. Henri (19, 20) has shown that a very thin layer of egg white is opaque to ultra-violet waves between 3000 and 2000 Angstrom units in length, and that in this region the opacity increases as the wave length decreases. If the absorption coefficient of egg white c... |
