212 THE GASTfilC JUICE. 



If the canula be removed, the fistulous aperture, which has 

 become established, gradually closes, and the connections 

 with the walls of the abdomen become absorbed. The sub- 

 joined Fig. indicates the union of the coats of the stomach 

 with the abdominal walls in forming the fistula. 



Fig. 90. 



If it be desired to experiment on the gastric juice of a 

 ruminant, the fistula must be established between the fourth 

 stomach and the abdominal wall. 



Numerous theories have been advanced in all times to 

 endeavour to explain the action which the food undergoes in 

 the stomach. Those which compared it to coction, fermenta- 

 tion, and combustion, for a time excited great attention, but 

 as they were mere hypotheses, often framed to support the 

 tenets of particular schools, they fell to the ground and were 

 forgotten. Keaumur made the first step towards ascertain- 

 ing the truth, and led the way for future observers, when 

 he pointed out that, in animals possessing a membranous 

 stomach, the triturating action which had been so much 



