The investigation of the biological action of homogeneous X-radiation of different wave-lengths was commenced because many clinical observations point to the existence of what has been termed differential action, although theoretical considerations do not support such a view. Differential action may be defined as the association of changes in living matter with certain special wave-lengths in the X-ray spectrum. The investigation was performed with the chorio-allantoic membrane of the embryo which. The X-ray spectrometer was used as a source of the different radiations. A fine pencil of X-rays impinges on a crystal, various component wave-lengths being reflected at corresponding angles connected by the formula the investigation of the biological action of bomogeneous X-radiation of different wave-lengths was commenced because m any clinical observations point to the existence of what has been termed differential action, although theoretical considerations do not support such a view. differential action may by defined as tbs association of changes in living matter with certain special wave-lengths in the X-ray spectrum. The investigation was performed with chorio-allantoic membrane of the embryo which. The X-ray spectrometer was used as a source of the different radiations. A fine pencil of X-rays impinges on a crystal, various component wave-lengths being reflected at corresponding angles connected by the formula
λ
= 2
d
sin θ (fig. 1, p. 405.). This gives a radiation which is very nearly homogeneous, but the energy is exceedingly small, a fact which has no doubt deterred many previous workers from using this method. The present paper is an extension and confirmation of certain observations contained in a preliminary communication to the '
Medical Journal of Australia
.' A selective action by different wave-lengths is described and the subject matter is arranged as follows: (
a
) The chorio-allantoio membrane and related structures are described; (
b
) the technical procedure of exposing the specimen to X-radiation is given, followed by (
c
) an account of the X-ray effects obtained, with details of their development and their relation to control experiments; (
d
) a systematic exploration of the X-ray spectrum is then described, giving microscopic results, which are expressed graphically, and details of confirmatory experiments, followed by (
e
) a brisk account of the microscopic examination. A general discussion (
f
) follows, in which the form, graphical expression, and the relationship of stimulation to destruction is considered. An apparent neutralisation between different wave-lengths in their biological action is also discussed and the technical procedure and form of tire graphs is considered in this respect. In the concluding remark (
g
) Zeleotive action is considered in relation to the atomic structure of the tissue and the main deductions are summarised.
THE KILLING OF COLON BACILLI BY X-RAYS OF DIFFERENT WAVE LENGTHS