62 JOURNAL OF THE [March, 



through the liver to a point near the oral cavity, or mouth, 

 which it sweeps nearly over ; and, winding round the liver on 

 its other side, and tlien going beneath that organ, it passes 

 beyond to the other side of the adductor muscle, in front of 

 which the vent rests in an open space which we will call the 

 cloaca. Here it voids its indigesta, which are immediately 

 committed to the sea. 



The liver, as you know, is bitter, a quality which the Roman 

 epicures prized highly. But we must dwell here a minute 

 longer, to describe the remarkable services which this large 

 organ renders to the stomach of the oyster. 



But, first, a word as to the oyster's food. A part is composed 

 of infusoria, often called animalcules, little creatures invisible 

 to our unaided eyes. These are easily digested. This is prob- 

 ably true also of the sporules of algae, and even the unicellular 

 alg?e themselves. It is not true, however, of a large part of the 

 oyster's food, such as the minute copepods, tiny crustaceans 

 with limy shells ; and the swarms of diatoms, very minute 

 plants with siliceous shields, which even resist the action of 

 nitric acid. An oyster's stomach is of itself a helpless affair. 

 It has no triturating surface, or secretors of solvent acid. But 

 it draws all it needs, from the liver. In the walls of the stom- 

 ach are openings continuous into small tubes in the renal mass. 

 Here are the bile secretions, and those of the pancreas ; also 

 the salivary glands, and the gastric follicles. We see, therefore, 

 why the stomach is placed inside the liver, — that organ is really 

 the laboratory of the necessary dissolvents of the oyster's food. 



Now it may be that one important ingredient which is con- 

 tained most richly in gastric juice, is supplied but feebly, if 

 at all, from this renal source. You who like tripe hardly need 

 be told that it is not strong food, but is of easy digestion, be- 

 cause of the pepsin it contains, derived from the gastric folli- 

 cles of the bovine stomach. The action of pepsin is probably 

 that of a ferment, while that of the other substances men- 

 tioned may be chemical and mechanical. Lately the microscope 

 has given a hint in this direction, and a hint to the scientist is 

 sometimes a Godsend leading to a discovery. Here you see 

 a little organ, like a tiny white thread of vermicelli. It lies 

 almost parallel to the intestines, and one end of it penetrates 

 into the stomach, at its lower end. This is called the crystal- 



