THE PANCREATIC JUICE. 253 



continuous change in the appearance of the cell-substance ; the granules of the inner zone dis- 

 solve to form part of the secretion ; new granules are formed in the homogeneous substance of 

 the outer zone, and pass towards the inner zone {Heidenhain, Kiihne and Lea). 



Changes in the Cells during Digestion. During the first stage (6 to 10 hours) the granular 

 inner zone diminishes in size, the granules disappear, while the striated outer zone increases in 

 size (fig. 187, 2). In the second stage (10 to 20 hours) the inner zone is greatly enlarged and 

 granular, while the outer zone is small (fig. 187, 3). During hunger the outer zone again 

 enlarges (fig. 187, 1). In a gland where paralytic secretion takes place, the gland is much 

 diminished in size, the cells are shrivelled (fig. 187, 4) and greatly changed. According to 

 Ogata, some cells actually disappear during secretion. 



The axially-placed excretory duct Consists of an inner thick and an outer loose wall of con- 

 nective and elastic tissues, lined by a single layer of columnar epithelium. Small mucous 

 glands lie in the largest trunks. Non-medullated nerves, with ganglia in their course, pass to 

 the acini, but their mode of termination is unknown. The blood-vessels form a rich capillary 

 plexus round some acini,' while round others there are very few. Kiihne and Lea found peculiar 

 small cells in groups between the alveoli, and supplied with convoluted capillaries like glomeruli. 

 Their significance is entirely 

 unknown. [They are probably 

 lymphatic in their nature.] 

 The lymphatics resemble those 

 of the salivary glands. "When 

 a coloured injection is forced 

 into the ducts under a high 



pressure, fine intercellular pas- w n 



sages between the secreting i ^ 



cells are formed (Saviotti's Fig. 187. 



canals), but they are artificial Changes of the pancreatic cells in various stages of activity. 1, 

 products.] ^ During hunger; 2, in the first stage of digestion; 3, in the 



[Number of Ducts. In second stage ; 4, during paralytic secretion, 

 making experiments upon the 



pancreatic secretion, it is important to remember that the number of pancreatic ducts varies in 

 different animals. In man there is one duct opening along with the common bile-duct at Vater's 

 ampulla, at the junction of the middle and lower third of the duodenum. The rabbit has two 

 ducts, the larger opening separately about 14 inches (30 to 35 cm.) below the entrance of the 

 bile-duct. The dog and cat have each two ducts opening separately.] 



Chemistry. The fresh pancreas contains : water, proteids, ferments,' fats, and salts. In a 

 gland which has been exposed for some time, much leucin, isoleucin, butalin, ty rosin, often 

 xanthin and guanin, are found : lactic and fatty acids seem to be formed from chemical decom- 

 positions taking place. 



169. THE PANCREATIC JUICE. Method. Regner de Graaf (1664) tied a cannula in the 

 pancreatic duct of a dog, and collected the juice in^'a small bag. Other experimenters made a 

 temporary fistula. To make a permanent fistula, the abdomen is opened (dog), the pancreatic 

 duct pulled forward, and stitched to the abdominal wall, with which it unites. Heidenhain 

 cuts out the part of the duodenum where the duct opens into it, from its continuity with the 

 intestine, and fixes it outside the abdominal wound. 



The secretion obtained from a permanent fistula is a copious, slightly active, 

 watery secretion, containing much sodium carbonate ; while the thick fluid obtained 

 from the fistula before inflammation sets in, or that from a temporary fistula, acts 

 far more energetically. This thick secretion, which is small in amount, is the 

 normal secretion. The copious watery secretion is perhaps caused by the increased 

 transudation from the dilated blood-vessels (possibly in consequence of the paralysis 

 of the vaso-motor nerves). It is, therefore, in a certain sense, a " paralytic secre- 

 tion" ( 145). The quantity varies: much, according as the fluid is thick or thin. 

 During digestion, a large dog secretes 1 to 1*5 gramme of a thick secretion (CI. 

 Bernard). Bidder and Schmidt obtained in twenty-four hours 35 to 117 grammes 

 of a watery secretion per kilo, of a dog. When the gland is not secreting, and is 

 at rest, it is soft, and of a pale yellowish-red colour, but during secretion it is red 

 and turgid with blood, owing to the dilatation of the blood-vessels. 



The normal secretion is transparent, colourless, odourless, saltish to the taste, 

 and has a strong alkaline reaction, owing to the presence of sodium carbonate, so 

 that when an acid is added, C0 2 is given off. It contains albumin and alkali- 

 albuminate ; it is sticky, somewhat viscid, flows with difficulty, and is coagulated 



