80 ESSENTIALS OF CHEMICAL PHYSIOLOGY 



appears in the form of small globules, surrounding or becoming 

 mixed with the protoplasmic granules that are ordinarily present. 

 Another remarkable fact which he made out is that after feeding an 

 animal on fatty acids the chyle contains fat. The necessary glycerin 

 must have been formed by protoplasmic activity during absorption. 

 The more recent work of Moore and Eockwood has shown that fat is 

 absorbed entirely as fatty acid or soap ; and that preliminary emulsi- 

 fication, though advantageous for the formation of these substances, 

 is not essential. 



We thus see how with increase of knowledge, due to improved 

 methods of research, a complete change has come over the ideas 

 which physiologists have held regarding this subject. It is not so 

 many years ago, that the physical change — emulsification — which 

 fats undergo in the intestine, was considered to be more important than 

 the chemical changes — fat-splitting and r.aponification. In fact the 

 small amount of chemical change which was supposed to occur was 

 regarded as quite subordinate, and of value merely in assisting the 

 process of emulsification. We now know that the exact converse is 

 the truth ; the chemical change is the important process, and emul- 

 sification the subordinate one. 



Bile aids the digestion of fat, in virtue of its being a solvent of fatty 

 acids, and it probably assists fat absorption by reducing the surface 

 tension of the intestinal contents ; membranes moistened with bile 

 allow fatty materials to pass through them more readily than would 

 otherwise be the case. In cases of disease in which bile is absent 

 from the intestines, a large proportion of the fat in the food passes 

 into the faeces. 



