FATTY PKINCIPLES. 73 



verted into glucose by mere addition of water, or by the action of 

 the pancreatic fluid in the duodenum. Or if not thus, this con- 

 version occurs in the liver. Its subsequent disposal has already 

 been explained. 



FOURTH DIVISION. 



Fatty Principles (Fatty Acids and Soaps). 



All the immediate principles of this class exist in a fluid state, 

 except that cholesterine, margarine, and perhaps stearine, are some- 

 times, in morbid conditions, found solid. They are also composed 

 of carbon, hydrogen, and oxygen alone, and in definite proportions, 

 and are found in both vegetable and animal organisms. There is, 

 however, no proof that they are the result of dis-assimilation, though 

 included in this class by Robin and Verdeil. 



The fatty principles exist in the tissues and fluids of the human 

 body in three entirely different conditions : 



1. Inclosed in cells, which constitute the fatty or adipose tissue. 

 This will be described in connection with the other tissues. 



2. They exist in chemical combination with other elements, and 

 hence can be detected only by chemical analysis. This is the case 

 with the fat in the organic matter of epithelium, nails, horn, and 

 hair. 



3. They form minute oil-drops, or "fat-globules," without any en- 

 velop, and in this form naturally enter into almost all the tissues, 

 except teeth and bones, 1 and into many of the fluids. They are 

 very minute, though of varying size, and 



possess a high refractive power. (Fig. 40.) Fi S- 40 - 



Thus the fatty principles are completely iso- 

 lated from all others, though they exist with 

 others in the same tissue or fluid. These 

 drops are, however, themselves always made 

 up of several of the fatty principles united 

 together, molecule to molecule ; and the 

 same is true of the fat in the cells of adi- 



Fat-globules. 



pose tissue. The only exceptions are the 



fatty elements of the brain, cholesterine in the blood, and certain 



1 Bones inclose fat in their cavities, but here it is contained in cells. 



