222 PHYSIOLOGY CHAP. 



conditions under which it acts in the intestine. We have shown 

 that it may co-operate in the emulsifying of fats, by partially 

 neutralising the acidity of the intestinal contents due to the 

 development of butyric and lactic acids, which are normally 

 present in the intestine in large quantities, owing to the fermenta- 

 tion of carbohydrates effected by the intestinal bacteria. 



Bunge in this connection attributes great importance to the 

 large amount of sodium carbonate, which causes the succus 

 entericus to effervesce when treated with acids. The greater the 

 acidity of the intestinal contents, the more active, according to 

 Bunge, is the reflex secretion from the crypts of Lieberkiihu, as 

 already assumed by Thiry and Quincke. 



He asserts that the intestinal mucous membrane tends rapidly 

 to neutralise the strong acids that are experimentally brought into 

 contact with it. Lombroso noted that when a solution of hydro- 

 chloric acid is passed into a short Vella's loop, its acidity is reduced 

 and practically neutralised in a few minutes. But if the acid be 

 combined with pepsin or protein, the neutralisation takes place 

 rather more slowly (U. Lombroso, C. Foa). How this neutralisa- 

 tion occurs is not exactly known. If we consider the quantity 

 of succus entericus excreted by the loop, and its potential alka- 

 linity, this is obviously much less than is required in vitro to 

 effect an equal reduction of acidity in the fluid in Vella's loop. 

 The same phenomenon does not occur when the higher fatty acids 

 are introduced into the loop instead of strong acids. In this case 

 the reduction of acidity is much less, and corresponds pretty 

 accurately with the potential alkalinity of the copious secretion 

 called out. We shall return to this interesting phenomenon as 

 demonstrated by Lombroso in our laboratory (1907-8), in treating 

 of fat absorption. 



The sodium carbonate of succus entericus comes from the 

 decomposition of sodium chloride effected by the parietal cells of 

 the gastric glands, from which hydrochloric acid and sodium 

 carbonate are formed. The first is secreted, the second absorbed 

 by the glandular lymphatics, and passes into the blood. This 

 hypothesis is confirmed by the fact which Baldi (1885) established 

 in a number of experiments carried out in our laboratory : to wit, 

 that the blood examined during fasting is less alkaline than that 

 during gastric digestion, and that the greater alkalinity observed 

 during this period depends on the increased quantity of sodium 

 carbonate. The diminished acidity of the urine (Beaunis) and 

 the greater alkalinity of the bile (Gaglio) in gastric digestion 

 evidently result from the increase of sodium carbonate in the 

 blood, when the gastric glands are forming and secreting 

 hydrochloric acid. It therefore seems to us reasonable (although 

 direct experimental proof is still wanting) to admit that there 

 is a certain relation between the amount of hydrochloric acid 



