272 THE ANIMAL. XII. 



and amido-acids, also bodies of the aromatic series, of which 

 indol, skatol, tyrosin, and phenol may be mentioned. 



/ CH \ . 



Indol, C (; H 4 CH, is a crystalline substance melting at 



\NH/ 



52, soluble in hot water, very soluble in alcohol or ether. It 

 has a peculiar odour and acts as a weak base. It is found 

 associated with skatol in faeces. It gives a characteristic red 

 precipitate with nitric acid. 



Skatol, methyl indol, C (i H 4 < /CH, also a crystalline 



* NH 



body, melts at 95. It is slightly soluble in water and readily 

 soluble in alcohol, ether, &c. It, like indol, is volatile in steam. 

 It has a most disagreeable faecal smell. With nitric acid it 

 gives a white precipitate. 



Phenol, C (; H 5 OH, and Pam-crcsol, C (; H 4 (CH 3 )OH, have also 

 been detected in faeces and result from bacterial action in the 

 intestines. 



The Bile. This product is to be regarded both as a 

 secretion and an excretion of the liver. It is continuously 

 poured into the intestines, though the rate of its discharge 

 varies with circumstances. A reserve is usually stored in the 

 gall bladder, with which many animals are provided. 



According to a table given by Gamgee, the amount of bile and 

 bile solids (in grammes) secreted per 24 hours per kilogram of 

 body weight in the case of different animals is as follows : 



Cat. Dog. Sheep. Rabbit. Guinea-pig. Man. 



Fresh bile 14-50 19-99 25-41 136-84 175-84 8 to 17 

 Bile solids 0-82 O99 1-34 2-47 2-20 0-19 to 0-28 



The liver is characterised by containing glycogen, C H 10 5 , 

 which may be regarded as a reserve nutritive material. Its 

 amount in the liver varies considerably, being greatly increased 

 after the consumption of food rich in carbohydrates, sometimes 

 rising to 10 or 12 % ; normally, however, it is probably be- 

 tween 1 and 4%. It disappears during starvation. It is an 

 amorphous, white, tasteless powder. 



