ELEMENTAKY EXPERIMENTAL PHYSIOLOGY 203 



CHAPTER LVII. 



INVESTIGATION OF THE MOTOR FUNCTIONS OF THE ALIMENTARY 

 CANAL BY MEANS OF THE X-RAYS. 



By A. F. HERTZ, M.A., M.D., F.R.C. P., Assistant Physician, late Demonstrator 

 of Physiology, Guy's Hospital. 



THE soft viscera are transparent and the salts of the heavy metals are 

 opaque to the X-rays. When therefore any part of the alimentar}^ 

 canal contains food mixed with such a salt, it casts a shadow on the 

 florescent screen, when X-rays pass through the body. Bismuth salts 

 are those generally employed, as they are not absorbed and do not 

 irritate the mucous membrane. The oxychloride is the most useful for 

 this purpose, as it is unaffected by the hydrochloric acid of the gastric 

 juice, and passes through the alimentary canal without influencing its 

 motor functions in any way. 



A small breakfast should be taken on the morning of the examination 

 in order that the stomach may bo as empty as possible when the 

 bismuth meal is eaten. Half a pint of bread and milk mixed with two 

 ounces of bismuth oxychloride forms the meal. A penny should be 

 fixed over the umbilicus by means of strapping, so that the position of 

 the stomach and intestine in relation to the umbilicus may be recog- 

 nised. It is unnecessary to take photographs, but the outlines of the 

 shadows seen on the screen should be marked out with blue chalk on a 

 superimposed piece of glass, and subsequently copied on to paper. 



Swallowing. The examination is begun in the vertical position. 

 A large mouthful of the bread and milk is swallowed, and its passage 

 through the oesophagus into the stomach is watched. For this purpose 

 the rays should pass in an oblique direction through the thorax from 

 the front of the right side to the back of the left side in order that 

 nothing should interfere with the view of the oesophagus, which 

 traverses the clear area between the shadow of the heart in front and 

 that of the spine behind. In the vertical position the food passes with 

 great rapidity to the back of the pharynx, and thence equally quickly 

 down the upper part of the oesophagus. A mouthful of ordinary size 

 occupies at any given moment between one and two inches of the 

 length of the oesophagus. If several mouthfuls are swallowed in rapid 

 succession the whole of the oesophagus becomes visible as a dark 

 shadow. 



When the fluid reaches the cardia, its rapid progress is arrested 

 owing to the sudden diminution in the lumen of the oesophagus. The 



