| The chemical digestive function in Silurus meridionalis was relatively deeply studied in this paper for the first time in our country. The results are as follows:(1)The numbers of mucosal ruga in alimentary tract of S. meridionalis larvae increase with their development; and the numbers of mucosa! ruga in foregut increases fastest. The results shows that the ratio of the height of mouth cleavage to its width becomes bigger with the development of the larvae: and when the ratio is 1, the feeding habit of the S. meridionalis larvae is changing.(2)The optimum pH of trypsin activity is 8.5-9.0, pepsin is 2.0-2.5, protease 8.5-9.0, and amylase is 8.0. The concentration of substrate for pepsin is 1.0% heamoglobin. for protease is 2.0%casin, for amylase is 1.0% dissolvable starch.(3)After intake of food, the trypsin activity in foregut increase, and at 1h, reaches the peak. In hindgut, this enzyme acrivity decreases, then begins to increase 4h later. The pepsin activity in stomach decreases after intake of food, subsequently it increases, and reaches the peak at 2h. The protease activity in foregut increases, and reaches the peak at 2h. The protease activity in hindgut increases slightly and stably after intake of food. The amylase activities in stomach, foregut and hindgut decrease after intake of food, but 4h later they begin to increase.(4)The dynamic changes of the digestive enzyme activities in tissues or organs of S. meridionalis were firstly studied in our country. The results show that the type of feed, the concentration of protein and starch in artificial stuff make an significant effect on the distribution of trypsin activity in tissues or organs of S. meridionalis.In the later period of the test(after 25d), the fish grow faster feeding on the raeat offish than on worm. The trypsin and protease activities in pancreas, pepsin activity in stomach and amylase activity in foregut and hindgut are lower in the group feeding on the meat than that in corresponding tissues or organs in the group feeding on worm. But the trypsin activities in foregut and hindgut and amylase activity in pancreas are significantly higher in the group feeding on the meat than that in corresponding tissues or organs in the group feeding on worm.(5)The fish grow faster in the group feeding the proper starch content feedstuff than in the other two groups. In the intermediate starch content feed group, the trypsin activities in foregut and hindgut show the (rend to decrease inthe later period of the test, but in the other two groups, the trypsin activities display the tendency to increase in the meantime.In the latter period of the test, the pepsin activities in stomach have the incination of increase in all three different starch content groups, but the pepsin activity in intermediate starch content group is higher than in the other two groups. The protease activities in pancreas in all groups tend to decrease. In foregut and hindgut in the intermediate and low starch content feed groups, the protease activities have the trend to increase, but that in high starch content group to decrease. The amylase activity in pancreas in high starch content feed group is stronger than that in the other two groups. In foregut and hindgut in the intermediate starch content group, the amylse activities run to decrease.(6)The fish grow significantly faster in the group feeding the intermediate protein content feedstuff(29.1%) than in the other two groups. During the whole test, the trypsin activites in pancreas show differences in ail three groups. In the intermediate protein content feed group, the trypsin activity in pancreas tend to decrease in the later period of the test, but in the other two groups, the trypsin activities in pancreas increase in the meantime. The trypsin activity in hindgut in low protein content feed group is significantly higher than that in the other two groups in latter period of the test. In this period, the pepsin activities in stomach have the tendency to decrease both in high and low protein content f...
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