502 



LECTURE XXI. 



above quantity of the mixture caused the secretion of 83.2 cubic centi- 

 meters. 



The digestive power of the gastric juice depends greatly upon the nature 

 of the food. Pawlow and his students studied the power of digesting 

 albumin on the part of both the gastric and pancreatic juices by Mett's 

 method. This consists of sucking up the white of an egg into glass tubes 

 of 1 to 2 millimeters bore and then coagulating it at a definite temperature. 

 These tubes are inserted under entirely corresponding conditions into the 

 digestive liquids, and taken out at the end of a definite period. Then, 

 by means of a millimeter rule and a microscope, the amount of albumin 

 that has become digested is measured. The following values are given 

 as examples of such an experiment : l 



At 8 o'clock the animal experimented upon was fed 200 grams of bread. 

 It secreted the following amounts of gastric juice with varying digestive 

 power: 



Time. 



Amount of Juice per Hour. 



Digestive Power. 



8-9 o'clock 3.2c.c. 8.0mm. 



9-10 o'clock 4.5c.c. 7.0mm. 



10-11 o'clock l.Sc.c. 7.0mm. 



The same dog was then fed 200 grams of raw meat: 



Time. Amount of Juice per Hour. Digestive Power. 



12 o'clock S.Oc.c. 5.37mm. 



1 o'clock 8.8c.c. 3.50mm. 



2 o'clock 8.6c.c. 3.75mm. 



Then 200 cubic centimeters of milk were fed to it: 



Time. Amount of Juice per Hour. Digestive Power. 



3 o'clock 9.2c.c. 3.75mm. 



4 o'clock , 8.4c.c. 3.30mm. 



A control experiment showed that the values given were in no way 

 caused by the order in which the food was eaten. It is evident from these 

 figures that the juice secreted after feeding with bread possesses the greatest 

 digestive power. Milk produces the weakest secretion of all. 



1 Cf. J. P. Pawlow: Die Arbeit der Verdaungsdriisen, p. 42. P. Chigin: Arch, des 

 sciences biol. Ill and Inaug. Diss. St. Petersburg (1894). 



