ACTIVITY DURING DIGESTION. i>1 



.simple fact, but it. is obvious that it involves a multitude of subtle 

 problems connected with the activity of the glands. 



The older methods were quite unable to give an answer to such a 

 question even as the following: Hew does the quantity of juice alter 

 with varying amounts of the same diet ? In other words, is the quantity 

 of juice directly proportional to the amount of food taken, or do those 

 two factors hold a different relationship to each other ? Asa matter of 

 fact, it was scarcely possible to solve this question, so far as the stomach 

 was concerned, by means of the simple fistula alone. The juice could 

 neither be separated from the food nor its quantity correctly deter- 

 mined. At present we are in command of perfectly accurate data 

 upon this point. The problem is easily solved on the dog with the 

 isolated stomach. We simply give it different quantities of the same 

 food and collect the corresponding quantities of pure juice. It appears, 

 from these investigations, that there exists an almost exact proportional 

 relationship between the quantity of juice secreted and the amount of 

 food taken. Thus, for raw meat, Dr. Chigin gives the following mean 

 values: For 100 grms. flesh, 2(>-U c.c. of juice were secreted; for -MM) 

 grins., 4(1-0 c.c. ; for 400 grms., IGG'O c.c. 



For a mixed diet, consisting of meat, bread and milk, the following 

 figures were obtained : 



I .1(1 ^TIIIS. meat \ 

 With :i diet of .Ml ., lin-ad 42'0 c.c. of juice escape. 



V :;nO c.c. milk ) 

 With doiilile tin- aliove i|ii;mtities. SH'2 c.c. 



Hence, we are justified in concluding from these figures that the 

 gastric glands work with great precision, inasmuch as for varying 

 quantities of diet administered, they pour out an exactly proportional 

 amount of juice, determined in the first instance by the quality of the 

 food. I regard this result as extremely instructive; it points, without 

 doubt, to the great accuracy and precision of the work of the digestive 



canal. 



And now we proceed to other questions : How does the work of 

 secretion proceed ? Is the requisite quantity of juice poured out once 

 and for all on the ingested food ; or, does the secretion continue so long- 

 as the food remains in that particular segment of the alimentary canal, 

 and does it vary regularly with the decreasing quantity and altering 

 properties of the mass ? 



These questions long ago gave origin to a multitude of investigations 

 from which it appears that the secretion of juice is continuous thixnigh- 

 out the whole period of digestion but with a varying rate of progress. 

 The data in question do not, however, give the impression of much 



