168 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



Finally, we maintain that particles between plates which move 

 back and forth on one another, and which are covered with bristles 

 all inclined in one direction, will invariably be carried in the direction 

 of the inclination of the bristles. If this be so, the modus operandi 

 of the stomach is as follows: (Plate III, Fig. 3) Food entering the 

 stomach is retained by the oesophageal valve and is carried backward 

 and upward between the lateral plates, the lower and middle lateral 

 pads, and the cardio-pyloric valve to the gastric mill: Here it is 

 partly comminuted and the greater part of it is carried forward by 

 the median tooth; some of it, however, is carried into the pyloric 

 chambers, and the fluids with minute particles of food filter backward 

 and forward from the chambers into the upper and middle canals. 

 The food entering the middle canal is carried backward between the 

 lateral valves to the gut. That entering the upper canal is carried 

 through it into the intestinal csecum. The larger particles of food 

 are retained by the marginal bristles of the middle pyloric chamber, 

 and the upward sweep of the bristles upon the posterior lobe of the 

 cardio-pyloric valve carries them again to the mill. The larger 

 portion of the food and that containing large pieces is retained in the 

 cardiac sac, and the fluids with small particles of food percolate down- 

 ward into the ventral part of the sac and are drawn by the inward and 

 outward movements of the upper and lower ventro-lateral cardiac 

 bars into one of the lower cardiac canals. From this canal the finest 

 particles pass into the upper cardiac canal and through it into the 

 mouth of the lower pyloric canal. The food passes through this 

 canal into the lateral pouch where it is subjected to a final sifting, 

 the most minute parts and the fluids pass down through the sieve 

 into the liver, while the less minute particles are carried upward 

 into the middle pyloric canal and through it into the gut. 

 Thus four streams of food material enter the intestine: 

 1. Two streams from the right and left branches of the dorsal 

 pyloric canal. These pass outward around the posterior dorsal 

 pyloric plate and the base of the dorsal valve into the capacious 

 intestinal csecum. 



