352 THE BILE AS A DIGESTIVE SECRETION. [BOOK II. 



With Bunge, we consider, as already stated, that this anatomical 

 fact establishes a strong presumption in favour of the view that, in its 

 long passage through the intestine, the bile must have serious duties 

 to perform, though we cannot admit that it negatives the view that 

 the bile is in respect of certain constituents (cholesterin and bile 

 colouring matters) an excretion. Altogether independent of such 

 arguments, however, we are in possession of facts which establish in 

 the clearest manner that the bile, besides being an agent in the 

 removal of waste products from the economy, is essential to the 

 normal course of the digestive processes of the small intestine: that 

 without its aid a most important group of alimentary principles the 

 fats in great part invariably escape absorption, though, it is true, 

 this departure from the normal state may, in some cases, be not incon- 

 sistent with the persistence of an apparently satisfactory state of 

 the general health. 



Action of bile Many observers have shewn that the bile obtained 

 on starch. f rom h uman biliary fistulas, if digested with starch 



solutions, for a great many hours, is able to convert traces of starch 

 into sugar. It is obvious, however, that in virtue of these traces the 

 bile can play no part in the digestion of starches, and accordingly it 

 has been found 1 that the faeces of dogs with biliary fistulas and fed 

 upon bread either contain no starch or only such small quantities as 

 occur in the case of normal dogs fed in the same manner. These 

 experiments are borne out by observations made on human subjects 

 with biliary fistulae. 



The bile of the pig appears, according to the observations of 

 Nasse 2 , to possess the power of dissolving raw starch. 



Action of bile The bile, containing no proteolytic enzyme, exerts 

 on proteids. no dj rec t ac tk>n in digesting the albuminous and albu- 

 minoid matters. Nevertheless, the bile must indirectly co-operate in 

 the digestion of proteids. When bile is added to the acid products 

 of gastric digestion (chyme), a precipitate is produced 3 , composed 

 essentially of a mixture of unchanged native albumins, and of bile 

 acids (especially taurocholic acid), which carries down with it pepsin 

 (Briicke). The important result of the admixture is, however, the 

 fact that, though the quantity of bile may be quite insufficient to 

 neutralise the acidity of the chyme, the proteolytic activity of the 

 pepsin is at once arrested (Briicke). The bile seems to have, there- 

 fore, the important function of arresting peptic digestion, and in this 

 way, as well as in others, of establishing the conditions which are 



1 Bidder und Schmidt, Verdauungssdfte, p. 222. 



2 H. Nasse, Canstatt's Jahresbericht d. PTiarm. 1859, n. S. 33 (quoted by Maly, 

 Hermann's Handbuch, Vol. vii. p. 177. 



3 Bernard, Legons de Physiologic Experimental, Paris, 1856, p. 422 ; Kiihne, 

 Lehrbuch d. phys. Chemie, p. 99 ; J. Moleschott, ' Ueber die Einwirkung der Galle und 

 ihrer wichtigsten Bestandtheile auf Peptone.' Untersuchung zur Naturlehre der 

 Menschen, Bd. xi. Heft 5, s. 2. 



