390 STRUCTURE OF THE PANCREAS. [BOOK n. 



The small buccal glands which lie in the substance of the 

 mucous membrane of the mouth, and whose secretion contributes 

 to " mixed " saliva, are formed, on a small scale, after the plan of 

 a salivary gland, that is to say, they are composed of a duct (or 

 ducts) and alveoli which in structure are similar to those of a 

 salivary gland. They further resemble the salivary glands in that 

 some of them are ' albuminous ' and some ' mucous.' 



219. The salivary glands have each of them a special 

 nervous supply of which we shall speak in detail in the following 

 section, and will here simply say that the fibres passing into the 

 glands are both medullated and non-medullated fibres, and that the 

 terminations of the fibres have not been as yet exactly made out ; 

 for, though it has been maintained by some observers that some of 

 the nerve-fibres end in the secreting cells, this has not been satis- 

 factorily proved. Numerous nerve-cells may be seen scattered 

 along the nerve-fibres where they pass into the gland at the ' hilus ' 

 whence the main duct issues. 



Of the nervous supply of the stomach, derived partly from both 

 vagi nerves, and partly from the solar plexus, we shall also have to 

 speak later on, we may here simply say that the fibres end for the 

 most part in a peculiar plexus between the circular and longitu- 

 dinal muscular layers, and in another peculiar plexus in the 

 submucous coat, the two plexuses corresponding to what we shall 

 describe in the small intestine as the plexus of Auerbach and the 

 plexus of Meissner. 



The Pancreas. 



220. The structure of the pancreas is so similar to that of a 

 salivary gland that though we shall not deal with the properties 

 and characters of the pancreatic juice until later on, it will be 

 convenient to consider the histology of the gland now. 



Whether as in man, in the dog and in most other animals it 

 forms a compact mass, or as in the rabbit is spread out into a thin 

 sheet, the pancreas is in all cases a compound racemose gland, con- 

 sisting of ducts and alveoli arranged in lobes and lobules. In man 

 the smaller ducts join one main duct, which running lengthwise 

 through the gland pierces the coats of the duodenum in company 

 with, and opens into the interior of the intestine by an orifice 

 common to it and to the bile duct. Not infrequently a second 

 but smaller main duct coming from the lower part of the head of 

 the gland joins the intestine lower down ; in the dog such a second 

 duct is a usual occurrence. In the rabbit the main duct does not 

 join the intestine with the bile duct, but at a considerable distance, 

 several centimetres, lower down, so that in this animal the bile and 

 pancreatic juice are not poured together into the intestine, but 



