18 MAiS-UAL OF OATTLE-FEEBIISra. 



substance 5s calculated by multiplying tlie percentage of 

 nitrogen found by analysis by 6.25 (6.25 x 16=100). 



The pliospliorus wliich always accompanies the albu- 

 minoids seems to be lield only loosely as phosplioric acid, 

 and uot to be an essential ingredient of them. 



Gii^LATiGEi^tous Substances. — The gelatigenous substances 

 constitute scarcely less of the weight of the body than the 

 albuminoids. 



They form the nitrogenous organic substance of bone 

 and cartilage, and make up the larger part of the mass of 

 the tendons, ligaments, and connective tissue, and of the 

 skin. By protracted boiling with water the gelatigenous 

 substances are completely dissolved, and converted into 

 glue. Their composition is very similar to that of the 

 albuminoids, except that they generally contain somewhat 

 less carbon (50 to 51 per cent.), and in case of cartilage also 

 less nitrogen (about 15 per cent.), w^hlle the gelatigenous 

 substance of the bones, tendons, and skin, on the contrary, 

 is richer in nitrogen (about 18 per cent.). The sulphur is 

 also either entirely lacking, or is present in smaller quan- 

 tity than in the albuminoids. 



IIoRNY Matters. — The horny matters are found chiefly 

 on the outer surface of the body, either in a thin layer, 

 as the epidermis (scarf-skin), or in well-characterized tissues, 

 as hair, wool, horns, nails, hoofs, claws, feathers, etc. The 

 average composition of all these tissues is very uniform : 



Carbon 50-51 per cent. 



Hydrog-en. , about 7 '' 



Nitrogen 16-17 " 



Oxygen , 22-20 '* 



Sulptiur 3-5 'i 



In the main, therefore, they differ from the albuminoids 



