LECTURE II. 



THE WORK OF THE GLANDS DURING DIGESTION. 



* 



The beginning of gland secretion is connected with the entry of food into 

 the alimentary canal The quantity of juice is proportional to the amount 

 of food The curve of secretion ; its importance and exact regularity- 

 Qualitative changes in the juice during secretion ; examples Methods <>!' 

 investigating the properties of the juices The gastric juice possesses a 

 constant acidity Meaning of the qualitative variations of the juices 

 Differences in the rate of secretion and in the digestive capabilities of 

 gastric juice, with diets of flesh, bread and milk Meaning of these. 

 differences The course of secretion and properties of pancreatic juice, 

 with the same diets The work of the digestive glands under the pro- 

 lunged influence of different dietaries. 



GENTLEMEN, Having considered the means by which the work of the 

 digestive glands may be more or less perfectly observed, we may now 

 turn to the work itself. By the aid of the older methods (the ordinary 

 gastric fistula and the earlier forms of pancreatic fistula), the first and 

 most elementary facts concerning the activity of the digestive glands 

 were established, not however without trouble and difficulty. Thus, it 

 was recognised by all authors that the glands only first began to 

 secrete when the food entered the alimentary canal, and, thanks to the 

 methods now at our command, hardly any physiologists doubt that the 

 activity of the glar.ds is strictly dependent upon the taking of food. 

 Every one of our experiments on dogs gives, in this respect, an unequi- 

 vocal and positive result. The isolated miniature stomach which, in 

 fasting animals, is peifectly empty, begins to furnish juice within a few 

 minutes after the animal has taken food. Similarly with dogs having 

 pancreatic fistula? : the quantity of juice, which is only two to three 

 cubic centimetres per hour, is increased to many times that amount 

 after the entry of food. This is a fact which has long been suspected, 

 but has only now been fully established. It is, moreover, consistent 

 with the requirements of the case. The juice is only poured into 

 the alimentary canal when the raw material, the elaboration of which 

 is demanded, makes its appearance therein. This is an apparently 



