CHAO: DIGESTIVE SYSTEM OF GUNNER 



tissue in the mesentery (omentum). It is also 

 dispersed into the liver in the vicinity of the 

 bile duct. Granulocytes are very abundant 

 around the pancreas and the hepatopancreatic 

 complex. The pancreatic duct joins the bile 

 duct near the entrance of the latter into the 

 intestine. The mesenteric membranes are more 

 prominent during late summer when fatty 

 tissue accumulates after the active feeding 

 season. 



LIVER. — The liver is divided into three 

 lobes. The central lobe, the largest one, is 

 triangular in shape and the tip continues to 

 the loop of sections I and II of the intestine 

 (Figure 1). In large specimens this lobe elon- 

 gates posteriorly and covers the spleen ven- 

 trally. Two smaller lobes extend lateral-dorsally 

 to cover most parts of the esophagus and the 

 intestine bulb. 



Histochemistry 



The PAS technique intensely stains the free 

 border and subborder of the intestinal epi- 

 thelium as well as the basal membrane and 

 goblet cells (Figure 15). The goblet cells and 

 the granules in the granulocytes and amoebo- 

 cytes give the strongest PAS reaction. Alcian 

 blue and toluidine blue methods stained only 

 the mucoid contents of the goblet cells, indi- 

 cating the presence of acid mucopolysaccharide 



and mucin. None of the methods showed any 

 secretory activity by the rodlet cells. There 

 were no distinct differences in these reactions 

 in the different portions of the intestine. 



Throughout the alimentary tract the pH 

 value ranged between 7.0 and 8.5. Acidic condi- 

 tions were not found in either fed or starved 

 specimens. Also, acid phosphatase tests were 

 negative in all cases. Alkaline phosphatase 

 can be demonstrated at the border of the epi- 

 thelium throughout the gut except anterior 

 to the eso))hageal-intestinal valve (Figure 21). 

 No positive reaction for alkaline phosphatase 

 was found in the epithelium of the gallbladder, 

 bile duct, or pancreatic duct. Alkaline phos- 

 phatase activity was intense in the intestinal 

 bulb and rectal valve, and it was most obvious 

 on the distal surface of the intestinal folds in 

 the presence of food particles. 



Food and Feeding Habits 



Gunners at East Point are abundant inshore 

 during the summer and may feed intertidally 

 during high tide. Gunner were observed swim- 

 ming in the kelp beds and using the kelps 

 Agarum, Alaria, Lami)iaria, etc. as shielter. 

 Juveniles (less than 100 mm SL) moved inter- 

 tidally or into tide pools where they use brown 

 algae A^cophijUum and Fucus as shelter. The 

 intestinal contents of 68 specimens (Table 1) 

 show that the cunner is primarily carnivorous 



Figure 21. — Alkaline phosphatase 

 test of the esophageal-intestinal valve 

 (V) of a well-fed 180-mm SL cunner 

 ( X 100. I.S.). E, esophagus; 1, 

 intestine. 





579 



