CHAP. i.J 



DIGESTION. 



265 



experiments on dogs that the pressure at which the bile is secreted 

 exceeds that of the blood in the mesenteric veins going to form the 

 portal vein. Hence, the limit of pressure, though so different from 

 that of the salivary glands, resembles it in this fundamental fact 

 that it exceeds the pressure of the blood in the capillaries of the 

 organ. The same peculiar vascular supply of the fiver renders it 

 difficult to draw any comparison between its vascular condition 

 during active secretion and that of the salivary glands, though 

 during digestion the liver is swollen and increased in weight, 

 apparently from an increase in the blood-supply. 



The quantity of bile secreted in man in the twenty-four hours 

 has been estimated to be exceedingly great, but the calculations are 

 based on very imperfect data. 



Pancreatic juice. In the dog the secretion of pancreatic juice 

 after food has been taken, follows the curve given in Fig. 49. There 

 is a sudden maximum rise immediately after food has been taken. 

 This at all events suggests very strongly some nervous action. 

 Then follows a fall, after which there is, as in bile, a secondary 

 rise, the causation of which may, or may not, be nervous in nature. 

 In the dog, there may be, during fasting, a complete cessation of 



7V 



-V 



!2|3|4|5l6|7|8|9|iO|ll|l2il3 l ,l4ll5il6| I I2l3|4|5|6i7|8i9|l0 



FIG. 49. DIAGRAM ILLUSTRATING THE INFLUENCE OF FOOD ON THE SECRETION OF 

 PANCREATIC JUICE. (N. 0. Bernstein.) 



The abscissa) represent hours after taking food ; the ordinates represent in c.c. 

 the amount of secretion in 10 min. A marked rise is seen at B immediately after 

 food was taken, with a secondary rise between the 4th and 5th hours afterwards. 

 Where the line is dotted the observation was interrupted. On food being again 

 given at C, another rise is seen, followed in turn by a depression and a secondary 

 rise at the 4th hour. A very similar curve would represent the secretion of bile. 



