PANCREAS. 



93 



Fig. 69. 



in all. The appearance of the frill of pyloric increase in length from the first three down- 

 caeca is shown in fi". 67, and one of the wards, and the third from the stomach is 

 bunches separate in fig. 68. generally the longest. They then gradually 



In the Salmon this apparatus of caeca is dimmish, slightly in calibre, considerably in 

 much more voluminous. It is not condensed length, to those furthest down the intestine, 

 around a particular portion of the intestine, which are about three inches long. Altogether 

 but extends linearly, from close to the duo- the secreting surface of these caeca must con- 

 denom for a distaiice of about eight inches siderably exceed that of the rest of the ali- 

 along the intestinal wall ; each caecum opens mentary canal, and the whole apparatus, taken 

 by its own separate orifice. There is no together, is next to the liver, by far the 

 coalescence or fusion, so that on looking on largest of the viscera. Each double row con- 

 the inside of the intestine there are seen as tains about thirty, so that altogether thecc 

 many orifices as caeca ; they form a double are sixty caeca, and as the average length of 

 row on each side, so that altogether there each caecum is 6 inches, the whole length 

 are four rows, and are arranged with the of secreting surface must be 390 inches, or 

 utmost regularity. The amount of secreting upwards of 32 feet. 



surface of these caeca must be very great; In their internal ultimate structure these caeca 

 some of them are ten inches long, and as exhibit considerable variety ; in many the mu- 

 bi" round as a tobacco-pipe; they rapidly cous surface is closely laminated ; in some it is 



covered with flattened, fused villi with 

 crypts thickly planted between their 

 bases. In the Herring (fig. 70.) the 

 structure is very peculiar : on looking 

 vertically on the internal surface it is 

 seen to be mapped out into hexagonal 

 and pentagonal cells about T ^ of an 

 inch in diameter, very evenly and geo- 

 metrically arranged, and each filled 

 with a mass of epithelium. The septa 

 between them appear to consist of sub- 

 mucous fibrous tissue, and on making 

 a section and looking at it laterally 

 they are seen to project between the 

 acervuli of epithelium, and rather 

 beyond them, and to have no epithe- 

 lial investment of themselves. The 

 masses of epithelium are seen to be 

 of a spheroidal form and very smooth 

 outline, though I could not distinguish 

 any basement membrane or capsule 

 wall of which they might be supposed 

 to be the contents, or any special 

 structure determining their outline. 

 I have thought this structure suffi- 

 ciently peculiar to give a figure of 

 it. A represents the appearance on 

 looking down on the surface; B, a 

 view of the wall in section, seen with 

 a lower magnifying power. 



Many anatomists deny the true 

 pancreatic nature of these pyloric 

 caeca, and assert that many fish pos- 

 sess, over and above them, a true 

 glandular pancreas, analogous in struc- 

 ture to the pancreas of higher animals. 

 Weber first described such an organ 

 in the carp, as interlaced with the 

 lobules of the liver, and, so to speak, 

 confounded with them, but having a 

 proper excretory canal opening into 

 the intestine by the side of the cystic ; 

 he also thought that he had seen 

 traces of a pancreatic duct in the 

 pike. Much more recently Alessan- 

 drini described the same excreting 

 duct, as also the volume and position 

 of the pancreas, in the same fish. 

 In the Silurus g/anis MM. Brandt and 



Portion of the alimentary canal of the Salmon (Salmo solar), 

 showing one double row of ccecal appendages and the pyloric 

 extremity of the other. 



a, oesophagus ; b, stomach ; c, pylorus ; d, small intestine ; 

 e, gall-duct. (One-third the natural diameter.) 



KutzeboLirg have taken for the pan 



