204 INFLUENCE OF BILE AND BILE SALTS 



some reason must exist for this apparent discrepancy in the 

 results. First, however, we must call attention to the extent 

 to which our analytical data can be trusted. Many times, to 

 be sure, duplicate results agree very closely, but experience 

 has taught us that, under the conditions of our experiments, 

 the limit of error is about 1 per cent. This means that where 

 50-60 per cent of proteid matter is digested, relative proteolytic 

 action may vary two points without having any special signi- 

 ficance (see Experiments 1, 2, 9, 18, 20, and 30). It is plain, 

 however, on carefully scrutinizing the preceding data, keeping 

 in mind what has just been stated, that in some experiments 

 bile manifestly tends to produce slight inhibition of proteolysis, 

 while in other experiments, apparently under the same con- 

 ditions, increased proteolysis results. It is further manifest 

 that this difference in action is to be connected mainly with 

 the character of the bile employed. Thus, it is to be noticed 

 that increased proteolysis is much more common with sheep's 

 and dog's bile than with ox or pig's bile. Such differences in 

 action might indeed be expected when it is remembered how 

 radically bile from different species of annuals differs in com- 

 position. Still with sheep's bile stimulation of proteolysis is 

 not constant, neither is inhibition always characteristic of pig's 

 bile ; but this is not strange when we recall how the bile from 

 a given animal may vary in composition with changes in 

 physiological conditions. Further, as Experiments 1 and 2 

 indicate, a given sample of bile may when present in one pro- 

 portion retard proteolysis, while a larger percentage will 

 accelerate digestion. This suggests the possible presence in 

 bile of two opposing factors, one tending to accelerate, the 

 other tending to retard proteolysis. Clearly such action as is 

 produced cannot be due solely to the characteristic bile-salts 

 which are contained hi such abundance in the bile. 



Bile is usually considered an alkaline-reacting fluid. Thus, 

 Neumeister * states that " the reaction of bile is alkaline ; it 

 contains about 0.2 per cent sodium carbonate and about the 

 same amount of alkaline-reacting sodium phosphate." It is 



* Neumeister, Lehrbuch d. physiol. Chemie, 2te Auflage, 1897, p. 195. 



