COMPARATIVE ANATOMY OF PANCREAS. 



99 



In Qadus and Scomher, the number is greatly augmented, and the complexity of 

 the gland increased by the division of the casca. In Scomher tJiynmis four large 

 trunks arise from the intestine, and divide into branches, each of which subdivide 

 and terminate at length in a tuft-like fasciculus of narrow tubular ceeca. 



In the salt-water Garfish [Lepisosteus osseus) of Georgia, the pancreas is situated 

 with its superior convex border in contact with- the inferior concave border of the 

 liver, which resembles in shape and appearance this organ in serpents. The inferior 

 border is in contact with the spleen. Upon the exterior it consists of numerous 

 short caeca, which radiating inwards unite together forming several branches, which 

 again unite and constitute one short duct, having a diameter almost equal to that 

 of the small intestine into which it opens. 



The duct branches of casca generally contain, especially after a meal of fish, a 

 cream-like fluid, which, under the microscope, is found to be a true emulsion, con- 

 taining innumerable minute globules of oil in a transparent fluid. The large opening 

 of the duct of the pancreas is so situated, just at the bend of the duodenum, that all 

 the digested food, after passing the stomach, must be sub- 

 mitted to the influence of its secretion and much passes 



into the duct and coBca. All the oleaginous matter must, 

 therefore, be brought into contact Avith the pancreatic 

 juice, and in this manner an emulsion is formed and pre- 

 pared for absorption. The emulsion is not found in the 

 stomach above the opening of the duct of the pancreas, 

 but exists in greatest abundance in its immediate vicinity 

 and within the casca. 



The structure of this gland in the fresh-water Garfish 

 of the swamps of Georgia, is constructed on a similar 

 plan; its caeca, however, are longer, and the branches 

 more distinct. The duct, branches, and caeca, contained, 

 in every instance after a full meal, a similar fatty emul- 

 sion. 



Fig. 11 represents the viscera, with the structure and 

 position of the pancreas of the fresh-water Garfish. 



This organ is very large in the Swordfish [Ziphias 

 gladius). Professor Grant states, in his Lectures upon Com- 

 parative Anatomy, that, in the Swordfish, this organ is 

 very large, and that it consists of innumerable small caeca 

 connected together by cellular tissue, in which ramify the 

 capillary vessels. These caeca form a reniform mass 

 which is surrounded with a muscular tunic and the peri- 



Viscera of a Fresh-Water Garfish reduced one-half diameter. B. Rough outline of the head. C, C. Pectoral fins. A. 

 Heart. F. Superior portion of the lung. M. Lung. T. Inferior portion of the lung. The lung of the Garfish is 

 a capacious fibrous sac which opens by a short trachea, high up in the throat, and extending nearly the whole 

 length of the abdominal cavity, terminates within a short distance of the anus. It lies between the posterior surface 

 of the liver and the anterior surface of the kidneys. When removed from the abdominal cavity, and fully inflated, 

 its diameter is about equal to one-half of that of the fish. In many respects its structure resembles that of the 

 Amphiuma means and other doubtful reptiles. L. Liver. N. Stomach. P. Pancreas composed of numerous cseca. 

 S. Spleen situated in a convolution of the small intestines. In many individuals I have found two spleens. R. 

 Inferior portion of intestinal canal. K. Anus. X. Anal fin. 



