316 



COMPARATIVE PHYSIOLOGY. 



going to the stomach, though this has little force as an argu- 

 ment against nerve influence. We may conclude the subject 

 by stating that, while the influence of the nervous system over 

 gastric secretion is undoubted as a fact, the method is not un- 

 derstood; and the same remark applies to the secreting activity 

 of the liver and pancreas. 



The Secretion of Bile and Pancreatic Juice.— When the con- 

 tents of the stomach have reached the orifice of the discharging 

 bile-duct, a large flow of the biliary secretion takes place, prob- 

 ably as the result of the emptying of the gall-bladder by the 

 contraction of its walls and those of its ducts. This is probably 

 a reflex act, and the augmented flow of bile when digestion is 

 proceeding is also to be trac'ed chiefly to nervous influences 

 reaching the gland, though by what nerves or under the gov- 

 ernment of what part of the nervous centers is unknown. 

 Very similar statements apply to the secretion of the pancre- 



4.0 



3.6 



3.4 



IZZST 



23|1|2|3|4|5|6|7|8|9 |10|ll|l2|l3|l4|l5|l6| l|2|3|4|5|6|7|8|9|l0 



Fig. 257. — ^Diagram to show influence of food in secretion of pancreatic juice (after 

 N. O. Bernstein). The abecissEe represent hours after taEing food ; ordinates 

 amount in cubic centigrammes of secretion in ten minutes. Food was talcen at 

 B and C. This diagram very nearly also represents the secretion of bile. 



atic glands, though this is not constant, as in the case of bile — 

 at all events in most animals. 



It is known that after food has been taken there is a sudden 



