20 PROFESSOR D. J. CUNNINGHAM 



This lies superficial to the proper circular coat of the duodenum, and very soon gives 

 place to the proper longitudinal coat of the intestine. 



5. In other cases all the pyloric longitudinal fibres, which do not dip into the 

 sphincteric ring to end there, pass on to the duodenum without any admixture of the 

 circular fibres of the stomach. 



6. The proper circular coat of the stomach is not continuous with the proper circular 

 coat of the duodenum, and is sometimes separated from it by a considerable interval. 



7. When circular fibres are continued from the stomach to the intestine they are 

 prolonged from the superficial part of the sphincteric ring, and are mixed with the 

 longitudinal fibres to form the feltwork already referred to. 



8. The arrangement of the component parts of the musculature of the pyloric canal 

 suggests that the longitudinal fibres by their contraction will tend not only to open the 

 pyloric aperture when the sphincteric ring is relaxed, but that they will likewise tend to 

 protrude the pylorus more fully into the duodenum and exert a pull on the initial part 

 of the duodenal wall, so as to drag it to some extent over the thickened end of the 

 pyloric canal. Such an action would clearly be advantageous to the proper passage of 

 material into the duodenum. 



Up to the present the physiologist has not recognised the pyloric canal as a special 

 portion of the stomach, and we have therefore no information as to the part which it 

 plays in the motor mechanism of the organ. That it has an important action cannot 

 be doubted : its powerful musculature bespeaks the fact. The question which naturally 

 suggests itself is, whether the entire length of the sphincteric cylinder is to be reckoned 

 with the expelling or with the retaining forces of the stomach, or whether it is to be 

 regarded as acting in both ways, and the sphincteric ring as being alone endowed with 

 a continuous sphincteric function. Clinical evidence would seem to point to the entire 

 muscular cylinder being under certain circumstances employed as a sphincter, and 

 thereby closing the whole length of the pyloric canal against the entrance of material 

 from the stomach. In those cases of pyloric stenosis in the infant which, of late years, 

 have attracted so much attention, it is not the sphincteric ring alone that is at fault 

 and prevents the passage of the gastric contents into the duodenum. The circular 

 musculature of the entire length of the pyloric canal, by its spasmodic contraction, leads 

 to the closure of this section of the stomach. On the other hand, we have noted that 

 in the adult it is more usual to find the sphincteric cylinder relaxed and the ring alone 

 contracted : and in this connection it is not without significance that if anything it is 

 more common to find the entire pyloric canal contracted and closed in the full than in 

 the empty stomach. 



But in considering this matter the outline drawings of Cannon (6), which show the 

 condition of the stomach during digestion, are of much importance. If reliance is to be 

 placed upon these in deciding a question of detail such as this, it would appear that the 

 pyloric canal in the cat is fully opened upon the arrival of the successive constriction 

 waves which pursue each other over the pyloric part of the stomach while the digestive 



