94- 



PANCREAS. 



creas a glandular body very like the liver in 

 appearance, stretched as a layer between the 



Fig. 70. 



Mucus membrane of the interior of the pyloric caecum 

 of a Herring (Clupcea harengus). 



A, the surface seen vertically, showing the honey- 

 comb appearance formed by the septa separating 

 the masses of epithelium. (Magnified 150 dia- 

 meters.) 



B, a section vertical to the surface, showing the 

 flattened spheroidal shape of the acuvuli of epithe- 

 lium, and the amount of projection of the septa 

 between them. (Magnified CO diameters.) 



folds of thegastro-hepatic omentum, enveloping 

 the cystic canal and accompanying it as far as 

 the intestine. These three examples of mala- 

 cocopterygious fish have no pyloric caeca, and 

 this glandular structure might be considered as 

 replacing them ; but Alessandrini has also de- 

 scribed in the sturgeon, the walls of whose in- 

 testinal canal are particularly glandulous and in 

 which the pancreatic cseca form an elaborate 

 apparatus, a proper pancreas with an excretory 

 duct opening into the intestine in the middle 

 of a tubiform papilla about an inch from the 

 pyloric orifice. In this last case Cuvier be- 

 lieved the bod}' indicated as the pancreas to 

 be a lobe of the liver. " The tubiform pa- 

 pilla," he says, " truly exists ; indeed I have 

 found two, besides that appertaining to the 

 choledoch duct. In one of the examples it 

 formed a sort of cul-de-sac ; in the other the 

 fibre which was introduced conducted to a 

 canal which took a direction towards the 

 liver. I have clearly seen an excretory duct 

 in a very large silurus, piercing the intestine 

 of the side of the choledoch ; but that canal 

 was, in my opinion, hepatic, for the glandular 

 substance taken as the pancreas was evidently 

 continuous with the right lobe of the liver, 

 and formed, as it were, a middle lobe ; its 

 appearance was in other respects the same, 

 except that its colour was rather clearer 

 in consequence of its substance being less 

 thick at that part. The duct discovered in 

 the pike certainly exists, as far as my re- 

 searches go ; but that, again, is an hepatic 

 canal, for I have not seen any body distinct 



from the liver from which it takes its origin, 

 or which could be considered as a pancreas. 

 The same must be said of the carp, where 

 Meckel could discover neither a pancreas nor 

 pancreatic duct, in spite of the indications of 

 Weber." Still more recently Stanuius has 

 enumerated many fish in which a parenchy- 

 matous pancreas may be found ; but the de- 

 scription added to his enumeration is so 

 meagre and general that nothing can be veri- 

 fied upon it. 



Reptilia. In the reptiles we make a great 

 approach to the structure of the pancreas of 

 higher animals both in general form and struc- 

 tural appearance. It exists in them all, and 

 generally maintains that intimate relation to 

 the end of the stomach and commencement 

 of the intestine which we see so constant in 

 birds and mammalia. 



In the Batrachia, the pancreas is situated 

 in a proper mesentery or meso-gastrium of 

 its own, extending between the lesser cur- 

 vatur of the stomach and the duodenum, 

 and, according to Cuvier, is more developed 

 in terrestrial batrachians than in aquatic, in 

 those that take their nourishment out of the 

 water than in those that hunt and seize it in 

 the water. In the Frog (Jig. 71.) the pancreas 

 is shaped not unlike that of the human sub- 

 ject, but its broad end is in the opposite 

 position ; it is about three quarters of an inch 

 long, weighs -27 of a grain, and is of a yellowish 

 white colour and soft consistence ; it is in 

 close apposition with the duodenum all the way 



Fig. 71. 



Pancreas of the Frog, shown by throwing up the 

 stomach, and exhibiting ilie under surface of the 

 mesogastrium. 



a, oesophagus ; b, stomach ; c, pylorus ; d, duo- 

 denum ; e, small intestines ; /, liver ; p, pancreas ; 

 s, spleen. (Natural size.) 



along. From near the large end it sends up 

 a process clothing and concealing the gall 

 duct as far as the gall bladder, the neck of 

 which it invests. The whole of the gall duct, 

 till the point of its immergence into the in- 

 testine, is thus concealed in the substance of 

 the gland, and it might at first sight be mis- 

 taken for the pancreatic duct ; but, by care- 

 fully nicking it and introducing a fine hair, the 

 hair may be passed up to the liver. The most 

 careful dissection could not reveal a proper 

 duct ; probably small ducts from different 



