of the Fishery Board for Scotland. 



35 



generally consisted of small Crustacea usually in process of activo 

 disintegration. Occasionally, I found what Mr Sim also found in 

 herrings caught in Aberdeen Bay during the years 1878, 1879, and 

 1880, viz., the small Sagitta bipunctata. One fact forced itself pro- 

 minently on one's notice, viz., that one might open a large number of 

 herrings and find nothing in their stomach. I did not examine a suffi- 

 cient number to determine the number that had or had not food in their 

 stomachs, but it was no uncommon thing to examine two dozen of 

 herrings taken haphazard and to find that only three, four, or six had 

 food in their stomach. There is a popular belief that the herring 

 does not feed during the spawning season, but this I regard as a 

 mistake, as one always finds a certain percentage of herrings with food in 

 their stomach during January and February. This much seems certain, 

 that they do not feed so voraciously when the ova and milt are reaching 

 maturity, and this seems to be borne out partly by the state of the 

 stomach and its contents, and partly by the analysis of the carbohydrates 

 to be found in the liver. In the specimens which I examined, there was 

 always a considerable difference in the naked eye characters of the food 

 found in the[cardiac and pyloric sacs respectively. In the former the food, 

 if it consisted of small crustaceans, was always less digested, less compact, 

 and the form of the animals could in most cases be made out. In the 

 pyloric sac, which has a comparatively thick muscular coat, and is usually 

 firmly contracted upon its contents, the food was broken up into a fine 

 mass, and, in the case of some of the crustaceous foods, it had a reddish 

 purple colour, due to the presence of a beautiful pigment which occurs in 

 considerable quantity in the eyes and other parts of these animals. When 

 the contents of the stomach were placed in alcohol, the pigment was 

 rapidly dissolved by it. The reaction of the contents of the cardiac and 

 pyloric sacs is acid. Sometimes a small quantity of an acid — at other 

 times nearly neutral — fluid was found in the cardiac sac, but none was 

 found in the pyloric sac. In the case of the cardiac sac, the food 

 extended down quite into the lower part of its tubular continuation, 

 which connects this organ with the swimming-bladder, but in no case 

 does it pass along the pneumatic duct, which has an entirely different 

 structure from the tubular, narrow, funnel-like prolongation of the cardiac 

 sac with which it is continuous. 



I subjected the contents of the cardiac and pyloric sacs to microscopic 

 examination, and of course the result obtained varied with the nature of 

 the food. If small fishes were present then their scales were always 

 found undigested, and in the case of crustaceans their chitinous invest- 

 ments remained undigested, and I also found numerous chitinous 

 appendages undigested in the contents of the intestine; but rarely cr 

 ever did I observe any chitinous hooks or scales in the contents 

 of the pyloric appendages. The muscular tissue of the crustaceans is 

 obviously rapidly digested, for it is rare to find any traces of striped 

 muscular fibres in the intestine. As in the case of the mammalian 

 stomach, one can generally find remains of the nuclei of cells, which, 

 consisting as they do of nuclein, are highly indigestible. The cells of the 

 crustaceans which contain pigment are abundant in the stomach, while 

 the reddish purple pigment of the eyes seems to resist the digestive 

 action of the gastric juice. In the intestine one almost invariably meets 

 with transparent rhomboidal crystals ; sometimes they are single, at other 

 times they are in rosettes or groups. They are insoluble in ether and 

 caustic potash, and are readily soluble in acetic acid. Entozoa are fre- 

 quently to be found in the stomach, some of them moving about freely 

 amongst the gastric contents, and others more or less firmly adherent or 

 imbedded in the mucus covering the mucous membrane of the stomach. 



