ANIMAL FLUIDS AND TISSUES. 443 



Pancreatic juice. There is no thoroughly reliable analysis of this 

 highly complex liquid on record. It contains from 3 to 6 per cent, 

 of solids, two-thirds of which are of organic, one-third of inorganic 

 nature. Among the organic constituents are a number (certainly 

 two, probably four) of enzymes: 1. Amylopsin converts starch into 

 sugar (this action is more energetic than that of ptyalin) ; 2. Trypsin 

 converts proteids into peptones (this action takes place in alkaline, 

 but not in acid solution, as in case of pepsin ; 3. Steapsin decomposes 

 fats into glycerin and fatty acids ; 4. An enzyme of which little is 

 known, capable of emulsifying neutral fats. 



Peces consist of that portion of the food which has not been taken 

 into the system by absorption, and is discharged from the body mixed 

 with some of the products of the biliary and intestinal secretions. 

 The odor depends largely on two substances, indol and skatol, and to 

 a less degree on the valerianic and butyric acids and the hydrogen 

 sulphide present. Indol, C 8 H 7 N, belongs to the aromatic compounds, 

 and is one of the products of the putrefaction of albumin. The 

 quantity of feces passed depends on the nature of the food taken 

 and on the energy of the digestive powers. A grown person, in 

 normal condition, discharges from 7 to 9 ounces daily. An approxi- 

 mate analysis of the feces of a healthy adult shows : 



Water 77.3 per cent. 



Mucin 2.3 



Proteids 5.4 " 



Extractives 1.8 " 



Fats 1.5 



Salts 1.8 



Resinous, biliary, and coloring matters . . 5.2 " 



Insoluble residue of food ...... 4.7 " 



Bone is chemically distinguished from other tissues by the large 

 quantity of inorganic salts which it contains. Dried bones contain 

 about 31 per cent, of organic matter combined with 69 per cent, of 

 mineral matter. Different bones (and even^ different parts of the same 

 bone) of the same person differ somewhat in composition; more- 

 over, the bones of a child contain somewhat more of organic matter 

 than those of a grown person, as may be shown by the following 

 analyses of the corresponding bone in children and a grown person : 



Child one year. Child five years. Man twenty-five years. 



Organic matter, 43.42 per cent. 32.29 per cent. 31.17 per cent. 



Tricalcium phosphate, 48.55 " 59.74 " 58.95 " 



Magnesium phosphate, 1.00 " 1.34 " 1.30 " 



Calcium carbonate, 5.79 " 6.00 " 7.08 " 



Soluble salts, 1.24 " 0.63 " 1.50 " 



