414 STRUCTURE OF THE PANCREAS. [Boon n. 



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 

 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. Some of these nerve-fibres thus passing to the gland 

 are destined for and end in the muscular walls of the blood vessels ; 

 they are vaso-motor fibres. Other fibres, we have reason to think, 

 are specially connected with the secreting cells. Though the 

 matter is not as yet clearly worked out, we may conclude, from the 

 appearances presented by silver as well as by methylene-blue pre- 

 parations, that delicate branches of naked axis-cylinders, branches 

 consisting as it were of a few fibrillas, end in arborescent ter- 

 minations, in the vicinity of and probably, though this is not 

 definitely proved, in contact with the bodies of the alveolar cells. 

 In this way probably nervous impulses are brought to bear on the 

 very substance of the secreting agents. 



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 pass for the 

 most part into a peculiar plexus between the circular and longi- 

 tudinal muscular layers, and into 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. Of these fibres, while many are destined for 

 the muscular fibres of the muscular coats, and others for the 

 muscular fibres of the blood vessels, some we have, as in the case of 

 the salivary glands, reason to think are destined for the glands, 

 and end in delicate arborescent terminations in contact with the 

 substance of the cells. 



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 the bile duct and opens into the interior of the intestine by 



