November 6, 1919] 



NATURE 



Moreover, the new knowledge reacts on older 

 information, shaping it for interpretation and 

 making it more valuable. From a knowledge, 

 for example, of the elastic constants of crystals, 

 the forces between the atoms themselves may be 

 calculated as soon as the architecture of the 

 crystal is known. It will be possible to make use 

 of facts concerning cleavage planes, occurrence 

 of certain natural faces and not of others, etching 

 Figures, and the like. Light will be thrown on 

 the meaning of valency and on all that lies at the 

 root of chemical action. If the atomic forces can 

 he calculated, an explanation of the form of the 

 wave-surface of light within a crystal will be at 

 liand. 



X-rays have been applied with ever-increasing 



success to medicine and surgery ; their extra- 

 ordinary power of revealing the interior of a body 

 without disturbing its exterior are beginning to 

 be recognised as a trustworthy aid to industry, 

 as, for example, in the detection of flaws of con- 

 struction otherwise invisible ; and their use in ob- 

 serving the crystalline state is already being con- 

 sidered as a probable and welcome aid to metal- 

 lurgical problems. But still the richest mode of 

 their employment is by the indirect methods of 

 pure science. Their unique properties help as 

 nothing else can to a knowledge of the relations 

 between radiation and matter, ether-waves and 

 electrons, atoms and the forces that bind them 

 together, which are among the greatest of the 

 fundamental problems of physics. 



X-RAYS IN MEDICAL SCIENCE. 



Bv A. C. Jordan, M.D., M.R.C.P. 



THE discovery of X-rays in 1895 was justly 

 hailed as one of the greatest scientific 

 marvels of any age. Medical men eagerly grasped 

 the possibilities of these rays, which enabled them 

 to see the internal organs of their patients actually 

 at work, hitherto impossible even to surgeons, 

 who in the course of their operations had the 

 organs exposed to view, but only under conditions 

 of anaesthesia. 



The first practical uses to which X-rays were 

 applied were: (i) In the detection and localisa- 

 tion of metallic foreign bodies, such as needles 

 and bullets; (2) in the detection and localisation 

 of metallic or other foreign bodies that had been 

 swallowed ; (3) in the diagnosis of fractures of 

 bones : this branch of radiologv has made enor- 

 mous strides during the war, and has led to a 

 vast improvement in the treatment of fractures 

 and to the saving of countless limbs ; (4) in the 

 diagnosis of calculi in the urinary tract and else- 

 where : these foreign bodies throw shadows which 

 have to be distinguished from concretions in the 

 l)owel and calcareous deposits : many pitfalls lie 

 in wait for the unwary observer, and the right 

 interpretation of these shadows, even at the 

 [iresent time, calls for skill, patience, and dis- 

 crimination ; (5) in the diagnosis of diseases of 

 the chest : the appearance of the normal move- 

 ments of respiration and of the beating heart 

 was closely observed, and as a result of these 

 observations upon healthy subjects this branch of 

 physiology has had, to a large extent, to be re- 

 written. The position of the heart and vessels 

 in the chest — in the midst of the air-filled lungs 



rendered accurate diagnosis difficult by the older 

 methods of physical examination, but by means 

 of X-ray examinations with the fluorescent screen 

 the mechanism of the heart has been closely 

 studied and its diseases accuratelv diagnosed. 



In regard to diseases of the lungs, pneumonia, 

 pleurisy, abscess of the lung, tumours, en- 

 larged glands in the chest, and many other con- 

 NO. 2610, VOL. 104] 



ditions produce characteristic shadows on the 

 fluorescent screen, and enable the site, nature, 

 and extent of the disease to be determined. In pul- 

 monary tuberculosis the aid which X-rays have 

 brought to its early diagnosis, and in defining its 

 extent, has proved of such value that this means 

 of diagnosing phthisis is playing an essential part 

 in the campaign in progress for dealing with this 

 scourge. A-ray study has shown that the first 

 changes which occur in the lung in this disease 

 lie so deeply buried in the chest — under cover of 

 a thick layer of healthy lung — that they are quite 

 beyond the reach of the older methods of detection 

 by percussion and auscultation. By the time the 

 stethoscope is able to discover the signs of con- 

 sumption, the disease is probably so far advanced 

 that the prospects of a cure are remote. The 

 diagnostic utility of X-rays has increased steadily 

 with the continued improvement in the apparatus 

 and the increased skill and experience of those 

 engaged in this branch of science. 



The correct estimation of fractures and other 

 injuries to bone and joints necessitated an accu- 

 rate study of the form and texture of normal 

 bones, as well as the individual variations that 

 occur in the conformation of bones and their joint 

 surfaces. This knowledge led at once to a most 

 important extension of the diagnostic powers of 

 X-rays — the recognition of disease in bone and 

 the differential diagnosis of many diseases of 

 bones and joints. 



So far we have considered radio-diagnosis as 

 dependent on differences of density among the 

 tissues. Bone, with its lime salts, is far more 

 opaque to >X-rays than muscle : consolidated lung 

 is more opaque than healthy, air-filled lung. At 

 first sight this precludes from the range of radio- 

 diagnosis a very important part of the body — the 

 hollow viscera constituting the digestive tract. 

 Very little information is to be gained from an 

 ordinary X-ray mspection of the stomach and 

 bowels, but the introduction of opaque substances 



