THE DIGESTIVE SYSTEM 



459 



(Alexis St. Martin) with an unusual bit of 

 accidental stomach surgery. This Indian 

 had been shot through the stomach with a 

 shotgun, and the remarkable thing about 

 the accident was that the load had not only 

 torn away the abdominal wall over the 

 stomach but had also taken a part of 

 the stomach as well. Beaumont plugged the 

 wound with a wad of cotton and waited for 

 his patient to die. To his surprise the pa- 

 tient not only recovered but tlie stomach 

 wall healed to the abdominal wall in such 

 a way as to leave a permanent opening, or 



firmed and a great deal more has been 

 learned. The famous Russian physiologist, 

 Pavlov, produced artificial fistulas in dogs 

 and then studied the rate of flow of the 

 gastric juice under various psychical condi- 

 tions (Fig. 17-6). In such fistulas a small 

 compartment of the stomach is separated 

 off from the remaining portion, but the cir- 

 culation and nerves remain intact so that 

 the fistula will respond normally. With such 

 an experimental animal Pavlov was able to 

 show conclusively what factors influenced 

 gastric secretion. Another operation which 



Fig. 17-6. Artificial openings into the digestive tracts of two dogs to illustrate how Pavlov performed 

 his basic experiments. The left dog is eating a "sham meal," while the right one is secreting gastric 

 juice from a "Pavlov pouch" into a container. 



fistula, as such openings are now called. 

 This gave Beaumont an unusual experi- 

 mental subject for the study of tlie func- 

 tions of the stomach. For years afterwards 

 he kept St. Martin close at hand so that 

 he could observe how digestion progressed 

 under all sorts of conditions. 



Since that time there have been many 

 cases where the esophagus has been closed 

 because of the accidental swallowing of 

 some strong chemical, making it necessary 

 to provide the person with a fistula in order 

 that he might receive nourishment. Many of 

 Beaumont's observations have been con- 



supplemented the findings with artificial 

 fistulas involved the severing of the esopha- 

 gus and the bringing of the cut ends to the 

 surface of the neck (Fig. 17-6). His dis- 

 coveries from this experiment were of great 

 importance. For instance, he showed that 

 if a dog were fed a meal which never 

 reached the stomach, since the cut esopha- 

 gus led to the outside at the neck, about 

 one-fourth of the normal flow of gastric 

 juice took place. He showed further that 

 this was due to reflexes, because the flow 

 ceased when all of the nerves to the stom- 

 ach were severed. However, if he placed 



