xi ACROSS THE BORDER 305 



After the discovery of Rontgen rays, their application 

 to medicine was soon seen ; and now there is scarcely a 

 hospital but makes use of the rays, not only for the 

 examination of inner parts of the body, but also for 

 treatment of certain diseases. The use of the rays to 

 show the position of embedded needles or other foreign 

 objects in the body, or to reveal fractures or dislocations 

 of bones, is obvious, but the extension of this method 

 of diagnosis has been even more valuable to the physician 

 than to the surgeon. Improvements in apparatus and 

 methods have made it possible to show, not only the 

 outlines of the bones, but also minute details of their 

 structure ; and more than this, a considerable amount 

 of detail of the internal soft parts of the human body 

 can now be examined by means of the rays. It is quite 

 easy to estimate in this way the size, shape and position 

 of the heart, to detect the earliest stages of congestion 

 of the lungs due to phthisis, to prove beyond doubt and 

 with perfect safety, whether a calculus (stone) is present 

 in either kidney, and to study the digestive canal 

 throughout its length. 



For this last purpose, the patient sits upright and 

 drinks a harmless dose of carbonate of bismuth. This 

 fluid is opaque to Rontgen rays, so that the shadow 

 thrown by it can be seen upon a* fluorescent screen. 

 The passage of the fluid from the mouth to the stomach 

 can, therefore, be observed upon the screen ; and any 

 obstruction in the food-pipe or deviation from the normal 

 course at once becomes apparent. The regular con- 

 tractions of the stomach by means of which the food 

 is expelled into the small intestine may be observed, 

 and a few hours later the course can be traced through 

 the large intestine. Before this development of dia- 

 gnostic methods, irregularities and obstructions in the 

 G.D. u 



