CHAP. V.] THE ACTION OF BILE ON FATS. 355 



perhaps, the decomposition into cholalic acid and amido-acids which 

 probably precedes absorption, bp.a function which is assisted by the 

 >recipitation which we have been considering ? 



The Action of the Bile on Fats. 



It has already been stated that the digestion of starchy and pro- 

 teid constituents of food proceeds normally in animals or human 

 beings with biliary fistulse, the faeces containing no larger quantity of 

 undigested starches or proteids than in the normal condition of the 

 body. The case is, however, very different with the fats. As Bidder 

 and Schmidt first ascertained with precision, and as has been abund- 

 antly and invariably confirmed, whenever the bile is cut off from the 

 alimentary canal, the faeces contain a large quantity of fat, shewing 

 that the processes which are necessary precursors of its absorption 

 have been materially interfered with. 



Bidder and Schmidt found that dogs with biliary fistulse absorbed 

 from 2 J to 7 times less fat than normal dogs. They also found that whilst 

 dogs on a meat diet yielded a milk-white chyle which contained 3-2 per 

 cent, of fat, in dogs in which biliary fistulse had been long established the 

 chyle, instead of being milk-white, merely presented an opalescent appear- 

 ance and, in one case, contained only (H9 per cent, of fat. Voit 1 shewed 

 that when dogs are fed on quantities of fat amounting to from 150 to 200 

 grms., 99 per cent, of the total amount is absorbed, only about 1 per cent, 

 passing into the faeces, whilst if the same amount of fat be given to dogs 

 with biliary fistulse, as much as 66 per cent, of the whole amount ingested 

 is excreted per anum. It is to this incapacity of utilizing the fats that 

 Voit ascribes the emaciation, as well as the ravenous hunger, of many dogs 

 with biliary fistula. 



The analyses of the faeces of human beings with biliary fistulse have 

 shewn that these invariably contain much fat; usually from 11 to 13 per 

 cent, of their weight. This fact will be referred to again. 



In describing the properties of the bile, we have referred to the 

 fact that it is able to dissolve small quantities of neutral fats, so that 

 it has, from time immemorial, been employed to remove grease stains 

 from coloured fabrics. That this slight solvent action of the bile 

 on the neutral fats plays a material part in the processes of the 

 intestine is, however, most unlikely. We have also referred to the 

 fact that the bile, when shaken with liquid fats, forms imperfect 

 emulsions, from which the oil soon separates. 



Although bile, pure and unmixed, possesses this imperfect emul- 

 sionising power, the case is very different if it be mixed at the 

 temperature of the body with free fatty acids. Under these cir- 

 cumstances, an acid emulsion is obtained, holding an excess of 



1 Carl Voit, ' Ueber die Bedeutung der Galle fur die Aufnahme der Nahrangsstoffe 

 im Darmkanal.' Stuttgart. Verlag der J. G. Cotta'schen Buchhandlung, 1882. 

 (Separatabdruck aus den ' Beitrdgen der Biologie, Jubilaumsschrift fiir Geheimrath v. 

 Bischoff.') 



232 



