276 THE ANIMAL. XII. 



Length of intestines Ratio of capacity 

 in feet. of st"inach. 



Horse ... 98 8-5 



Ox ... 187 71-0 



Sheep ... 107 67'0 



Pig ... 77 29-0 



The Urine. This is, perhaps, the most important excretion 

 of the Animal body, since in it are the nitrogenous waste pro- 

 ducts, the water and the soluble mineral salts derived from the 

 food or the breaking down of tissue. It is formed (or, probably 

 more correctly, extracted) from the blood by the kidneys, which 

 contain several albuminous bodies, fat, xanthin, urea, uric acid, 

 glycogen, leucin, inosit, taurin, and cystin. The last-named 

 substance has the composition C (i H 1 . 2 N. 2 S 2 4 . Urine varies 

 greatly in composition with the breed of animal, the food, 

 quantity of exercise, amount of water taken, and many other 

 circumstances. In carnivora and man, urine is usually acid, 

 while in herbivora it is neutral or alkaline. 



The specific gravity varies greatly ; its determination furnishes 

 an important means of estimating the total solids present. In 

 the case of human urine, variations from 1-002 to 1-040 have 

 been observed. The characteristic constituent of urine is urea 

 or carbamide, CO(NH. 2 ). 2 , which is more abundant in the urine 

 of carnivora than in that of herbivora. 



/NH CO 



Creatinin, C 4 H 7 N 3 O, or NH:(V xanthin, 



>N(CH 3 ).CH. 2) 



CgH^N^a, and smaller quantities of allied substances also 

 occur in the urine of man and some mammalia. 



NH.CO 



Uric acid, C 8 H 4 N 4 f or CO^ C.NH\ 



\NH.C. NH/ 



occurs abundantly in the excrements of birds and ser- 

 pents, also in the urine of carnivora and man, and, to a 

 very small extent, in that of the herbivora. Uric acid is a 

 dibasic acid, and both the acid and its acid salts are very 

 slightly soluble in water. In certain diseases, e.g., gout, de- 

 posits of uric acid and urates are formed in the body. 



