SECTION OF INTERNAL ANATOMY OF HEAD 169 



When the nostril is opened, the membrane by 

 which the cartilage and whole cavity of the nose 

 is lined is seen. By the colour of this membrane, 

 and the lining of the eyelids, we are assisted in 

 determining the amount of congestion of blood in 

 the mucous membrane which lines the air passages 

 and the bowels. This cavity on both sides is 

 occupied by two bones, which, in consequence of 

 being rolled up in the form of a turban, are called 

 the turbinated bones. 



/, /. The septum nasi, cut off at the lower part to exhibit the 

 spongy turbinated or turban-shaped bones, filling the 

 cavity of the nostrils. Part of the cartilage is re- 

 moved to display them. They are as thin as gauze, 

 and, like it, perforated into a thousand holes. 

 Between them are left sufficient passages for the 

 air. 



If these gauze-like membranes were unrolled, 

 they would present a very considerable surface. 

 On every part of them there is spread the delicate 

 fibres of the olfactory, or first pair of nerves, 

 which are the organs of smell. It is by this ex- 

 quisite sense of smell that the horse selects such 

 food as is best calculated for his nutriment, and 

 is enabled to reject what is poisonous. By smell 

 he judges of the quality of his food in a domestic 

 state. The horse will recognise his master or 

 favourite groom by the sense of smell, and fre- 

 quently expresses such recognition by a neigh. 

 These cavities intensify sounds issuing from the 

 larynx the organ of voice ; the sound reverberates 

 through them, and increases in loudness as through 

 the windings of a French -horn. All the air which 

 passes to and returns from the lungs must go 

 through the nostrils, as he can breathe through 



