ii EXTERNAL DIGESTIVE SECRETIONS 95 



various nitrogenous compounds, inosite, lactic acid, neutral fats, 

 volatile fatty acids, uric acid, and mineral substances. The 

 composition of the human pancreas is according to Oidtmann 



Water . . 74'53 per cent 

 Organic Substances ... . 24-57 

 Inorganic Substances 0-75 ,, 



The most important substances it contains (the chemical 

 nature of which is still wholly unknown) are the three or four 

 zymogens, which are readily converted into their respective 

 enzymes, on which the digestive properties of the pancreatic juice 

 depend. 



The pancreatic secretion differs entirely in its physical 

 characters and composition according as it is collected in a 

 temporary fistula of Wirs ung's duct, or from a permanent fistula. 

 In the first case it is stringy and syrupy, forming in the cold at 

 a gelatinous mass, from which a fluid serum separates out. 

 This gelatinous mass readily dissolves in dilute acids. Owing to 

 the amount of protein, the pancreatic juice thus obtained coagulates 

 on heating. The secretion from the permanent fistula is more 

 fluid, and contains a smaller amount of organic matters. Both 

 the one and the other juice have digestive properties, but we 

 must hold with Pawlow that it is only the secretion from a 

 successful permanent fistula that represents the normal secretion, 

 since the pancreas is highly sensitive to all the lesions inevitable 

 in making a temporary fistula. 



The quantity of juice that escapes from a fistula in a given 

 time is very variable, and therefore very difficult to estimate. 

 Some hold that the human pancreas secretes 150 c.c. per diem. 



This appears to us to be too low an estimate. Since Pawlow 

 obtained 300-350 c.c. of juice from a dog that weighed about 

 20 kgrm., it is probable that a man would secrete over 500 c.c. 

 per diem. 



The actual reaction of the pancreatic juice, which is almost 

 neutral (Farkas), must be distinguished from the potential reaction, 

 which is, on the contrary, intensely alkaline, and equivalent, in 

 the dog to l/10n NaOH. Pawlow has observed that the alka- 

 linity of the pancreatic juice is equivalent to the acidity of the 

 gastric juice, and therefore suffices to neutralise the acidity. 



Normal pancreatic juice contains a large amount of protein. 

 According to Zawadsky that collected from a fistula in a woman 

 operated on for pancreatic tumour contained in 100 parts- 

 Solids . 1.3-59 per cent 



Total Organic Substances .... 13-25 



Albumin 9-21 



Ash . 0-34 



